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Alias Season 4:

Favorite Episode

In this area I'll talk about my all-time favorite episode. I'll try to explain why I think it's the best and why it's important to me personally.

Season 4: Episode 1- "Authorized Personnel Only, Part 1"

Sydney, on a train, in lingerie, flirts with a man to get into his … briefcase. He unlocks it, revealing a canister containing an unstable isotope. She knocks him out and takes it, runs into the corridor. A thug follows and is about to push her off the train...

Shanghai: 72 hours earlier … Sydney, in a naughty schoolgirl outfit, escapes with a contact into a club's bathroom. It's a mission gone bad, a fellow agent is killed, and in order to escape she makes her contact dress like a goth.

In LA, Syd is berated for violating protocol by Director Chase and stripped of her classified clearance. Sydney then quits the CIA. In Washington, Vaughn and Weiss talk about his meltdown after discovering Lauren's treachery. Vaughn says he's quitting.

Sydney walks down a subway, opens a secret doorway and enters an office. Director Chase is there and welcomes her. She explains Langley approved this black ops division only months ago. Dixon, Jack, Vaughn are all there -- a team handpicked by Sloane. Chase privately tells Syd that they need Sloane's contacts -- and the team is a safeguard against Sloane's potential treachery.

Sloane explains that their covert unit is like the CIA's own SD-6, called APO -- Authorized Personnel Only. Their first mission targets a Russian scientist named Yuri Kamarov, who wants to sell an isotope to an unknown buyer on a Belorussian train. Vaughn will act as the buyer while Syd grabs the isotope. She's openly disdainful toward Sloane.

On the train, Syd barges in to Kamarov's room claiming that it's her room. Vaughn poses as Kamarov and meets the buyer, who works for a Mr. Vadik, while Sydney occupies the real scientist. The buyer recognizes Vaughn and puts a thug on him as he leaves. Vaughn signals Syd, who swipes the isotope. Vaughn beats the thug and races to save Syd. He throws her assailant off the train. They make love. After, he asks Syd what happened at Wittenburg. Syd flashes back -- she's reading a top-secret document as Jack enters.

Season 4: Episode 2- "Authorized Personnel Only, Part 2"

Sloane plans for Syd to talk to Nadia about Vadik, whom she once tracked. Sloane says that Nadia quit the intelligence business and returned to Argentina after they found a Rambaldi artifact and handed it over to the US government. In Argentina, Nadia tells Syd that she won't return but that Vadik's right hand is Tomazaki.

At home, Syd tells Vaughn about Wittenburg -- she learned that day that her father had killed her mother, Irina Derevko.

Tomazaki has disappeared. They learn that five years ago he unsuccessfully tried to steal the Shintaro sword from a London museum. Sloane suggests they steal the sword as bait. At Dixon's suggestion, they enlist Marshall. In the museum, Syd triggers the alarms but manages to steal the sword and, with Jack's help, escapes the police.

Later Jack tells Sloane that he didn't tell Syd everything in Wittenburg.

Dixon arranges to sell the Shintaro sword to Tomazaki in Rio de Janiero. Tomazaki's jailed thug tells Jack that Vadik is Tomazaki. At the agreed meeting, Tomazaki kidnaps Syd. Vaughn asks Nadia for help. Tomazaki asks a perplexed Syd how she found out about the hit. He tortures her. He says he was supposed to assassinate her but the day before the hit, his client was killed.

Nadia steals a key card from a Tomazaki associate and saves Sydney from drowning during the water torture. Tomazaki knocks her out. He attacks Syd with the sword but she runs him through. Before he dies, he says that Irina Derevko hired him to kill her.

Sloane announces that Nadia has joined APO. Syd tells Jack that Tomazaki had the contract. He doesn't know why Irina wanted Syd dead. Vaughn comforts a shaken Syd.

Nadia and Syd travel to Moscow, where Syd had Irina interred. Syd tells Nadia she has no idea who killed her. Nadia swears that she'll kill whoever murdered their mother.

Season 4: Episode 3- "The Awful Truth"

In Nassau, the Bahamas, Syd and Marshall arrive incognito at a bank under the pretense of creating an account while Vaughn and Dixon create a diversion. When the manager leaves momentarily, Syd and Marshall access an account.

Back in LA, Weiss and Nadia - who's now living with Syd - hit it off at a party Syd hosts. Jack crashes the party, says her Bahamas mission paid off, they have info on Bishop, owner of the account, and Valta. He wants to know if she told Nadia that he killed Irinia. Syd hasn't but thinks it best if she does.

Sloane says Valta, a computer that will revolutionize info gathering from satellite networks, was stolen from the NSA headquarters 10 days prior by Martin Bishop, who will be deliver it to a German terrorist group. Bishop, a British ex-pat living in Spain, awaits final payment before delivering Valta. The team must recover or destroy the computer.

They determine that Valta's whereabouts are stored on a powerful server on Bishop's estate in Andalusia, Spain, and they can only hack into it from the inside. Once in Spain, the team sets a trap for Bishop using Syd as bait - she portrays a mysterious woman caught in an overturned car. Bishop rescues her and invites him to her home. He tells her not to wander the grounds.

Jack administers a psych test to Nadia. He tells Sloane that he's learned enough to deal with the problem.

With Vaughn monitoring the situation, Syd sneaks away and finds the server in the basement. She determines that Valta is located at Malaga's Alameda Yards in container C0717. Bishop's suspicion is raised when he runs into Syd as she returns to her room. Sloane sends a team to Malaga to find Valta and tells Jack that Syd may be in trouble.

At Alameda Yards, a CIA team destroys Valta, but Weiss is captured. Bishop is informed of the raid and learns that someone accessed his server. An alarmed Syd signals for help, and Vaughn and Dixon go in only to find the house empty. Marshall tracks Bishop by his cell phone signal.

Jack tells Nadia he doesn't blame her for Irina's infidelity and hands her classified documents before they are dispatched to Spain, where they liaison with Vaughn. Bishop holds both Weiss and Syd captive. Bishop hopes to offer them up to the terrorist group as a replacement for the computer. Syd breaks free of the ropes and beats the guard -- Weiss now realizes she's black ops. They go after Bishop. Vaughn meets up with Weiss. Syd trails Bishop, jumps on top of his car and shoots him through the roof. He slams the breaks and she tumbles off. He's about to shoot her when he is killed by Nadia, who pumps a few extra rounds into him. She says he was the one who killed Irina, their mother - Jack lied to her!

Later, Jack admits to Syd that he adjusted details in the documents to manipulate Nadia and give her closure. He says a satisfying lie can do more good than the awful truth.

Season 4: Episode 4- "Ice"

With Vaughn and Dixon covering, Syd tries to buy a bio-weapon called Ice 5 from an American at a foreign bazaar. When thugs disrupt the deal, Syd bolts with the man. As they're running, his leg snaps off. He's then shot - and literally explodes.

Marshall later determines that the biological agent, which the man had swallowed, actually "freeze-dried" him, crystallized him from the inside. He worked as a relief worker in a Montenegro hospital run by Fenton Keene, who secretly developed Ice 5. Sloane wants the team to obtain a viable sample of Ice 5.

At Syd's home, Nadia finds a photo of Irina holding a baby. Nadia asks Sloane who the baby in the picture is. He dodges the question.

Syd visits the hospital as a representative of Omnifam and does the grunt work, while Weiss and Nadia put together a list of potential buyers. A patient comes in showing symptoms of Ice 5 infection but the nurse, Kyra MacLane, says he was in a car accident and won't let Syd help treat him.

Vaughn, disguised as a priest with a black eye, flirts with MacLane and convinces her to make confession. Fenton appears, tells Vaughn that he's her brother and asks to see the man in the car accident. Meanwhile, Syd swipes MacLane's card key and passes it to Dixon, who makes a copy and gives it to Syd.

Syd searches the lab and finds 14 tanks of Ice 5. To her horror, she spies Fenton testing it on human subjects. Weiss reports that they found a buyer in Damascus. They find MacLane is really Fenton's sister, and that they're both former IRA. Vaughn feels she can be turned and approaches her during confession.

When they meet, MacLane says her brother has done awful things. With Syd listening in, Vaughn tells MacLane that he's haunted by thoughts of his former wife, whom he killed after she betrayed him. MacLane realizes Vaughn is government. He tells her that he can protect her from her brother should she turn on him.

MacLane takes Vaughn to the lab, where Fenton clobbers him. He's forces MacLane to inject Ice 5 into Vaughn's eye. Syd enters and rescues Vaughn. During the fight, Fenton stabs his sister by accident. She dies in Vaughn's arms, but forgives him before passing.

Jack asks Nadia for the photograph. He said Irina told her she was holding her niece. The next day, he recalls, he proposed. He says he chooses to believe it's true, but says that everyone needs to find our own sense of closure.

On the return flight, Syd, sensing a disconnect, tells Vaughn he can talk to her whenever he wants.


Season 4: Episode 5 - "Welcome to Liberty Village"

A Russian-speaking man steals a device from an armored truck. He goes home to a suburban neighborhood and greets his loving wife in English.

At APO, Sloane says the stolen object was an EMP, an electromagnetic pulse weapon. Marshall says it can destroy any electronic equipment in a 10 mile radius and has a repeatable core. The thief, Yuri Karylko, has ties to October Contingent. In related news, German authorities have arrested a Chechen couple, the Tabakovs, who said the October Contingent had made overtures to them. Syd and Vaughn are to pose as the Tabakovs to infiltrate the Contingent, identify their mission and retrieve the EMP. Marshall gives Syd a wristwatch that can send their GPS coordinates and is capable of short burst transmissions. Sloane, meanwhile, tells Jack to contact Alexi Vaselyvich.

In Moscow, Karylko gives Syd and Vaughn new identities -- they are to be known as David and Karen Parker - and takes them to Liberty Village. Marshall tracks their journey to Training Sector 56B, a former Russian military base that now resembles a suburban American neighborhood. Syd and Vaughn arrive at the neighborhood. They are taken to their new home and introduced to the neighborhood.

Karylko, going under the name Tom, says Syd and Vaughn will be tested to see if they can portray Americans convincingly. Marshall picks up Syd's transmission and identifies the "neighbors" as assorted terrorists. Sloane wonders why the Contingent is dealing with terrorists and why they're in a government training ground.

Ironically, Tom tells Syd and Vaughn that they seem a little cold. He gives them a gun. While Syd goes jogging, Vaughn practices assembling the gun. Syd runs into Tom, who tells her that the neighborhood is heavily guarded.

Jack meets Alexi and asks if the Russians still run the old base. Alexi bargains with Jack, expecting something in return for extracting Syd.

Tom gives Syd and Vaughn wedding rings so they look more like a couple. He takes them to a car dealership, their mission is to buy a convertible. The dealer sees the ring, asks how he popped the question. Vaughn spins a tale that moves Syd. The dealer says another couple is also interested in the car. The winning couple gets to move on in the program, he says. The losing couple dies. He gives them a gun to assemble, both couples race to assemble it.

Jack opens a book from Irina's collection of 1st editions. The NSA had cracked the orders the KGB encoded in the books. He tells Marshall that the NSA missed something and puts him to work on it.

The couples shoot it out in the car dealership. In the melee, Vaughn loses the gun. Syd picks it up and kills the woman. She then jumps in the car and runs down the man. Later, Syd notices that the watch is broken. She and Vaughn kiss in the shower.

Marshall finds the code in the ink of a period within an ellipsis. After magnifying it, he sees that it contains a protocol related to one of Irina's operatives, codename Sentinel. Jack says Sentinel is a dead end, a deceased agent. Jack gives the book to Alexi, who says he hasn't heard from Irina a long time. He also says he has an aircraft waiting to extract Syd and Vaughn.

Tom prepares to send Syd and Vaughn to Chicago, where they are to gain access to the servers of Pierce Financial. Tom's plan is for a "redistribution of wealth" after an attack on the U.S.

Marshall receives word that the Germans have moved the Tabakovs to a maximum security prison - and assumes the Russians have been informed also.

Tom shows Syd how to use the EMP. He then receives a call from his wife. Knowing her cover is blown, Syd knocks him over the head with a vase and they fight. In another room, Vaughn battles another thug. Syd and Vaughn escape outside where a helicopter has them pinned. Syd triggers the EMP and the chopper falls from the sky.

Afterward, Sloane thanks Syd and Vaughn. He says Russian authorities deny an American training ground ever existed in their borders but off the record they've expressed gratitude for APO's assistance in taking down the October Contingent. Privately, Jack says his suspicions regarding Sentinel are accurate, and the Russians are searching for Irina Derevko. Sloane says they'll have to move up their timetable. Syd and Vaughn canoodle on the plane home.

Season 4: Episode 6 - "Nocturne"

A woman teaching English to foreign students believes she's being watched. Convinced she can't escape, she draws a gun and kills herself.

Syd and Vaughn, playing hockey when they get the call, report to Sloane. He explains that when Nancy Cahill, an undercover narcotics agent, shot herself, her last words were "Tell them it's funny." Cahill's husband Jason, also an agent, has gone off the grid. Syd and Jack are to search the Cahill's Amsterdam apartment for clues.

In the apartment, Syd unlocks a crawlspace door and follows a passage to a room plastered with disturbing drawings. She's suddenly attacked and bitten in the throat by a feral Jason. Jack shoots him dead.

As Syd undergoes a battery of tests, the doctor says the Cahills came in contact with a drug that caused an acute melatonin imbalance, which incited their acts of extreme violence. Syd's diagnostics indicate that she's fine.

Sloane says Langley wants to find the drug, who manufactured it and what it's used for. Marshall traces the calls Nancy made and begins reconstructing erased files on her laptop. Weiss says Jason was trying to determine what he was infected with, even after Nancy locked him in the closet.

Syd can't sleep and begins hallucinating. Her temperature reads 111.

Jason's files indicate he had a meeting scheduled in Bucharest with "The Count," a drug supplier. Syd mission is to pose as a Cahill associate and meet The Count. Dixon tells Sloane it's a mistake to send Syd out so soon. Sloane harshly reprimands him.

In Bucharest, Syd has a recurring hallucination of a spider. Marshall calls Jack to say the drug's incubation period is a few days, like a virus, and permanently alters brain chemistry. Jack tells Vaughn that they should have her in sight at all times. At the meeting, Syd imagines Vaughn kissing someone. They take The Count into custody, and admits he recently delivered samples of a drug called "Nocturne" to Jason. Once the delusions begin, there's no stopping it. Syd, increasingly off-kilter, imagines Sloane threatening her. Syd chokes The Count, who offers that the drug came from Prague and was an old sample meant to be destroyed.

Nadia finds a group called Grappig, which means "Tell them it's funny" - an affiliation of biochemical scientists in Prague led by Dr. Letuza. Nancy had found out where it came from but was too far gone. Vaughn says Letuza may have developed a remedy if he knew he made a bad batch. In Prague, Vaughn searches for Letuza's files. Syd grows fearful that Jack will kill her. She asks to be tied up and Jack obliges. She imagines Jack comparing her to Irina. Syd head butts him, takes his knife and cuts herself loose.

Vaughn finds vials of antidote and returns to see Syd crying over an immobile Jack. She says she killed him, but it's a trap. She has a gun, forces him to his knees. She says their relationship is a cruel joke at her expense and that she's scared she will betray him again. She fires but the gun has no bullets. They fight. She beats him with a pipe. Jack wakes and subdues Syd with a sleeper hold. Jack had taken the bullets out! Vaughn administers the antidote.

In LA, Sloane says Interpol has raided Letuza's office and eradicated the Nocturne threat. Sloane admits to Dixon that sending Sydney was a tactical error. An angry and humiliated Dixon says he never saw the nature of SD-6 because his only failure was that of imagination -- he never imagined a person as thoroughly toxic as Sloane could exist. When Sloane's true motive reveals itself, Dixon promises to be there.

Syd and Vaughn kiss in her hospital room. She sees a spider on her bed. Vaughn brushes it away and says spiders are good luck.

Season 4: Episode 7 - "Detente"

In Irkutsk, Vaughn learns from a contact that Russia has produced a breakthrough explosive called Black Thorine. The contact suspects his superior stole it and sold it, and gives Vaughn the man's bank account number. Soldiers arrive and shoot the man, Vaughn escapes with Syd's assistance.

Syd arrives home to find Sloane visiting Nadia. Despite Nadia's objection, Syd kicks him out, saying he can't be trusted. She only took the APO job to watch him. Nadia realizes Syd hasn't reconciled the past.

At APO, Sloane says that money was deposited into the account by Boris Tambor, an oil magnate who moonlights as an arms dealer. He's currently in Monte Carlo. Jack says he sits at a high stakes poker table every night at 9. Their mission is to get into his suite, find out where he keeps the black Thorine and how he plans to move it.

Syd confides to Dixon that she may not be able to work with Sloane. Dixon says he dreams of his dead wife Diane every night; she tells him to do the right thing. That's how he makes peace with Sloane -- he doesn't ignore the past, but he makes the right decision today.

As they shoot targets at a firing range, Syd tells Nadia that she needed to know her mother and so understands Nadia's desire to know Sloane.

In Monte Carlo, Syd inserts a micro camera into the suite and gets a visual on Tambor, who's watching a soccer match - not going to the gaming table. Nadia and Syd notice perfume, a purse, magazines. They realize he's got a girlfriend. Deducing that the woman is bored, pissed off because she's being ignored and sitting in the bar, they see their opening.

Dressed up to party, Nadia and Syd identify the girlfriend from her perfume. They befriend the woman and she takes them up to the room, past security. Syd clones his PDA hard drive while Nadia chats up Tambor.

In LA, Sloane is angry at them for taking risks. Syd gets indignant at what he deems "unacceptable." Everywhere she looks, she says, she's reminded of Francie and Danny. Marshall has broken the hard drive's encryption and finds out that Tambor will sell the vial on his yacht, Argento, which is sailing in Turkish waters in the Black Sea. It's stored in a safe within a safe in a cabin below deck. Marshall gives Syd a device that will allow her to read the safe's combination through his clothes.

Jack lobbies for Sloane to allow Syd and Nadia to work together again. They swim to the yacht and sneak on board. Syd uses the combination reader while Tambor makes the deal. Sloane recognizes the buyer as Leo Orissa, the head of a Russian crime syndicate. Nadia opens the safe - revealing eight canisters of Black Thorine.

Orissa ambushes Tambor, whose girlfriend turns on him. Tambor is killed as Syd and Nadia escape to the water. Sloane tells Syd she has to trust him and advises her to go back on board. Confronting Orissa, Syd says she works for Arvin Sloane, which sends fear into the man. Syd catalogues Sloane's depravity. Orissa offers up the location of the lab. Meanwhile, Nadia disposes of Orissa's thugs. The lab, Orissa says, is in the Ukraine. Tambor's girlfriend shoots Orissa and fights Syd. With an assist from Nadia, Syd kills her.

Nadia tells Syd she's always been alone. Now she's glad to work on a team. Sloane assumes Syd wants a transfer. Syd says she will never forgive him. "I'll see you tomorrow," she says.

Season 4: Episode 8 - "Echoes"

Before the team meets, Nadia gushes about Weiss to Syd while Weiss moons about Nadia to Vaughn. Sloane recuses himself from the upcoming mission because it involves an operative that he is not authorized to engage. He puts Jack in charge and leaves the briefing. Jack says the target is Syd's old nemesis Anna Espinoza, a former K-Directorate Agent and Rambaldi follower, presumed to be dead. Intel indicates that Espinoza is to receive something from an associate, Milos Sabine, in Brussels. While reviewing the files, Nadia gets lightheaded and walks out. Syd, Dixon and Marshall are to observe the meeting and bring her in if the opportunity exists.

At lunch with Nadia, Syd talks about past encounters with Anna. Nadia says she saw something awful when she was connected to Rambaldi last year -- she had a vision that she and Syd were aiming guns at each other. She pulled the trigger and shot Syd, she says, who seemed to expect it.

Syd takes a call - it's from Anna, who's actually sitting behind Nadia. She kidnaps Nadia and demands that Syd pose as her in Brussels for the meeting with Sabine.

In Brussels, Sabine says he wants to get his money's worth before he gives her the item. He tells Syd to kill Willem Karg, who's in a hotel bar, photograph the body as evidence and bring back his right index finger. If she's not back in 40 minutes, she won't get the package.

Syd poses as a prostitute and lures Karg to go up to his room - where Vaughn and Dixon wait. They cut off his finger to save his life. She presents it to Sabine; he gives her the "last remaining sample."

Anna has her thug Mr. Turner brand Nadia with the Rambaldi symbol.

Marshall identifies the sample as the Dante Compound, a rare putty that when mixed with V/X gas and other nerve agents, mutates them. Marshall believes Anna works for the Cadmus Revolutionary Front, an offshoot of the Covenant. They've been trying to acquire the compound for a year to make a chemical bomb. He suggests they talk to Sark.

Sydney doesn't think they should follow through on a plan to give Anna a replica of the Dante Compound because she may kill Nadia. Sloane says Anna won't kill Nadia - he says it's not her destiny. Syd realizes that this is about Rambaldi. Jack agrees that Syd should meet with Anna.

Anna and Sydney meet in a Beverly Hills boutique. Syd gives her the compound. Anna gives Syd a remote car key and tells her to go to the 4th floor of a parking structure across the street. Anna threatens Syd, who starts a knock-down, drag-out brawl that ends in a virtual stalemate. Realizing that they're getting nowhere, they make the exchange. Syd finds Nadia locked in a car trunk.

Vaughn visits Sark in the federal pen. Sark asks if he killed Lauren because of espionage or infidelity. Vaughn hits him and asks why the CRF has made repeated attempts to contact him. When Sark goes silent, Vaughn has him shipped to Alder Penitentiary, where he is to spend all his days in dark solitary confinement.

Syd returns with Nadia. The surgeon says they can fix the brand. Nadia relates that Anna says that she and Syd will be torn apart. Syd explains that according to their mother, the outermarkings of the Rambaldi symbol are her two daughters, the center is the object over which they'll do grave battle with each other. Only one of the daughters will survive. Syd says some of these predictions have come true, but that she doesn't believe in it. The people who do, she says, are dangerous.

Jack injects Sark with a tracking device (and explosive) while he sleeps in prison. As Sark is transferred, the vehicle is attacked. - it's a set-up. A man helps Sark escape.

Syd hears chatter about a meeting between the CRF and an administrator of a Russian chemical facility named Vorich. Syd thinks Anna may be there. Jack tells her to take Nadia for surveillance only. If Vorich is there, he may have a sample of V/X. Sloane is afraid that if Syd and Nadia go on the mission together and Anna has her way, only one will return. Marshall tracks Sark to Johannesburg.

In Johannesburg, the team raids what they think is CRF headquarters, only to find Sark in an empty room guzzling champagne. He agrees to locate CRF leadership in return for something.

In Estonia, Nadia and Syd find Vorich, who's quickly killed by Anna. Nadia battles Mr. Turner as Syd chases Anna. Turner falls on his knife, Nadia twists it until he reveals in his dying breath why the CRF is assembling the bomb. Syd thinks she's cornered Anna, but it turns out to be Nadia. Anna then shoots Nadia in the back. She falls as the life ebbs from her.

Season 4: Episode 9 - "A Man of His Word"

Sloane and Syd watch over the injured Nadia, who remains stable in a medically-induced coma. Syd tells him that Anna has the bomb.

Sark is brought before Sloane, who asks him to retrieve that bomb. According to Sark, Ushek Sanko, the leader of the CRF, will take possession of the bomb from Anna Espinosa. Sark agrees to retrieve the bomb on the condition that he be allowed to view Lauren Reed's body - and that Vaughn opens the coffin.

Lauren's body is stored in a CIA mortuary lest her death become public knowledge. Vaughn opens the lid. Sark, studying her bullet wounds, deduces that Vaughn killed her.

Sloane tells Syd that, according to Rambaldi, Nadia can't die by Anna's hand. Anna sneaks into the hospital to assassinate Nadia, but Sloane secretly had her moved to a different room. Syd gives chase but Anna escapes through a window, using a firehose to break her fall.

Nadia is moved to the CIA sickbay. Sloane tells Jack to eliminate Anna. Marshall observing the security camera tape of Karg's confession to Nadia, sees Anna observing from the shadows - which explains why she wants Nadia dead.

Vaughn and Syd take Sark to meet Sanko at a club in Venice. Syd impersonates Lauren in order to accompany Sark. She kisses Sark (biting him on the lip) to titillate Sanko. Before Sanko can reveal any info, Anna shoots and kills him. Syd handcuffs Sark to a railing while she and Vaughn look for Anna, who frees Sark and extracts the tracking device/explosive from his neck.

Over dinner, Anna tells Sark that she killed Sanko because he wouldn't pay her enough for the bomb. She wants to contact a buyer, Michele Gignon, an arms dealer with whom Sark has a relationship, and suggests they form a partnership.

Jack makes the risky decision to inject Nadia with a counter-agent, waking her from the coma. He gleans the necessary info from her and passes it to Syd. The doctor recognizes the drug in Nadia's system and tells Sloane.

When Sark and Anna meet Michele in Venice, Syd and Vaughn make their move. Vaughn recovers the bomb. Sark turns on Anna, and leaves her to Syd. They have another hand-to-hand showdown. This time, Syd slaps the cuffs on her, pistol-whipping her for good measure. Sark, however, escapes.

An angry Sloane confronts Jack about forcibly waking Nadia from the coma. Jack quotes Sloane, saying his orders were "to do what it takes." He also refers to the prophecy, saying it wasn't Nadia's time. Nonetheless, Sloane says that Jack should have told him that he put his daughter at risk. Jack says Sloane puts Syd at risk every day. Their relationship appears severely damaged.

Season 4: Episode 10 - "The Index"

Sydney, Weiss and Nadia discuss Nadia's upcoming birthday. Nadia doesn't want to celebrate; she doesn't even know when her real birthday is.

At the team briefing, Sloane tells them about the Blackwell Index, an encrypted disc once owned by the CIA that contains incriminating evidence against many government officials and corporate heads. The CIA was never able to crack it, and now the disc has been stolen. The team is to steal a Decoder disc housed in an evidence room in a Paris police precinct. Vaughn is passed over for the mission - he's heading to Arizona to visit his comatose uncle.

Dixon approaches Syd, saying that he refuses to follow Sloane blindly and now double-checks all information - he's even installed a wiretap in his office, and though the line is encrypted, he's traced a call Sloane made to Miles Deveraux, a former Alliance agent. Dixon then goes to Director Chase, who says he needs more proof that Sloane is reforming The Alliance. Dixon asks for Syd's help in decoding the conversations.

In the Arizona hospital, a nurse named Rosemary tells Vaughn that his uncle frequently spoke about Vaughn's father, Bill. She gives Vaughn an envelope from the uncle, meant for Vaughn's father. Later, Vaughn opens a locker in a Mesa bus station and finds a diary with entries dating to 1982. Bill Vaughn died in 1979.

Syd shows Dixon a mini-disc burner, created by Marshall, which will produce a corrupted copy of the Decoder Disc. They agree to give Sloane the phony copy.

In Paris, Sydney, who is dressed as an American punk, vandalizes Weiss's vehicle in order to get arrested. Dixon arrives as Sydney's lawyer and quickly shoots the guard with a tranquilizer.

Nadia remotely guides Syd to the evidence room of the police station. She finds the Decoder while Nadia scrambles the security camera. Sydney makes the corrupted copy and flees from the police. She races to the roof and leaps on to a helicopter piloted by Weiss.

At APO, Syd convinces Sloane to hold a dinner party for Nadia's birthday. At the party, Syd gets a phone call from Dixon. She retreats to Sloane's office and transmits Sloane's decoded conversations with Devereux. The conversation revealed Sloane's contact with Deveraux, and an implied reformation of SD-6. As Syd is about to leave, she sees Nadia standing before her. Nadia accuses Syd of using her but Syd enlightens her. Dixon, armed with the decoded conversations, convinces Director Chase that Sloane must be taken down.

In Brussels, Sydney, Nadia, Dixon and Chase observe Sloane as he enters an abandoned building. Inside, Deveraux presents the Blackwell Index, which is to be cracked using the decoder that Sloane now has, to a group of men.

Sydney, Dixon and Director Chase run into the building, leaving Nadia to wait for them in the car. As the three burst through the door, they find Sloane alone in a deserted room, with a laptop. They discover that Sloane is actually conducting surveillance as Jack meets with Alliance members. Syd realizes that Jack has the false Decoder just as Devereaux begins to doubt Jack. Nadia speeds to the meeting and arrives in time to takes out the Alliance members, saving Jack's life.

Miles away, Vaughn tries to speak with his comatose uncle. "Is he still alive?" Vaughn asks. No answer. Vaughn asks the head nurse if he can speak to Rosemary. The nurse says nobody by that name works there.

Sloane, in his home office, inserts the Decoder Disc into his laptop, revealing the Blackwell Index. He then calls Jack and tells him it has everything they need -- and more.

Season 4: Episode 11 - "The Road Home"

Disguised as a French woman, Sydney acquires a microchip from a contact named Thomas Connelly in a Paris restaurant. Before the deal goes down, an assassin shoots Thomas. Vaughn, watching from the shadows, prevents him from killing Syd. As Vaughn and Syd corner him, he slits his own throat with a knife.

In the APO office, Sloane tells Jack and Sydney that the information downloaded from the microchip reveals that a Biometric Targeting Device is being developed at a secure facility in Austria. If attached to a weapons system, this device could facilitate the targeting of an individual based only on a DNA sample or a biometric scan. It is the next generation's sniper.

Sloane tells Sydney that the assassin worked for Sasha Korjev, a vicious arms dealer involved in developing the new targeting weapon. Sydney's mission is to retrieve the Biometric device in Salzburg, Austria. Sloane gives Dixon the task of locating Korjev but Jack volunteers to do it himself.

Weiss suggests that Vaughn is mistaken in believing that his father, Bill Vaughn, is still alive. Vaughn swears it was his father's handwriting in the diary. Weiss hands Vaughn a paper with the name Frank Murdoch, an ex-Special Forces man in San Diego whose shop is mentioned in Bill's journal.

Jack later admits to Sloane that the CIA wants Korjev assassinated and he can get closer to him than Dixon can. Jack adds Korjev should've been eliminated years ago, when he "had the chance."

In an Austrian club, Sydney befriends Sam, an American busboy, and uses his I.D. to get into the basement. She finds a status report revealing that the Biometric device has been moved and is scheduled to leave the country in the morning. The report also states that the device had been installed on a weapon.

A guard shoots at Sydney. She decks him and overhears on his walkie-talkie that the weapon is stored at the Delongpre shipping yard - and that the guards are now after Sam. After Marshall confirms that Sam is a civilian, Syd escapes with him. She leaves him with her Austrian contact so he can be put in a protection program.

In San Diego, Vaughn visits Frank, who shows him a photo taken with Bill in 1982. Frank says that Bill was ruthless enough to shoot him in the back, then smoke a cigarette over his bloody body before walking away. Vaughn later lies to Weiss, saying he never found Frank.

Sydney's contact in Salzburg arrives with a stranger to pick up Sam, and she senses something's not quite right. Realizing his betrayal, she pounds them senseless and reluctantly explains her mission to Sam. She asks for his help to get to the shipping yard.

In Angola, Jack meets Korjev, who wistfully remembers Jack as a mentor. Later, Korjev speaks of Jack's betrayal. Jack says he was the one betrayed and garrots him.

At the shipping yard, Syd discovers that the weapon has been attached to an assault chopper. She tells Sam to wait in the van. Syd defeats the guards in combat and attempts to retrieve the weaponized mini-copter -- but the system activates and locks on to her. As it fires, she runs through a maze of narrow aisles and crates.

While Sam waits, he's wounded by a Korjev henchman. Syd tackles the gunman but the chopper locks on to her again. Sydney quickly uses the gunman as a human shield. The chopper, hovering closer, senses the corpse and, believing its mission is accomplished, settles on the landing pad.

Sydney arrives in the APO office in time to see Jack preparing to leave. As Jack mentions that he is planning to have dinner before heading home, Sydney asks if she could join him and they leave together.

Season 4: Episode 12 - "The Orphan"

It's 1992. A man sneaks into a Buenos Aires orphanage in the middle of the night and tries to kidnap one of the girls. A young Nadia resists him and escapes.

Vaughn shares his father's journal with Sydney. He asks her for access to the Operational Archives. Later, Vaughn decodes an address in Lisbon that may help reveal the mystery of his father's life.

At APO, Sloane says that the Belorussian Institute of Science had developed a next gen optical component called the Amplifying Glass, which can boost a laser pulse. It can enable a CD player's laser to shoot a plane from the sky or slice a tank in half. A Jakarta faction has employed Cesar Martinez, an Argentine resident, to acquire it for them. Nadia knows him - they were once partners in crime.

Nadia reports that Martinez is a freelancer, and he earned his reputation with the execution of former Argentine intelligence officer, Roberto Fox. Their mission is to outfox Martinez and obtain the Amplifying Glass at a party held in the Minsk Institute of Science. As the team leaves the room, Nadia admits to Sydney that she knows Martinez.

A blonde Sydney arrives at an elegant party in the Institute of Science. She charms an architect, whose Blackberry holds the building's blue prints and project files. After scanning his PDA with Marshall's help, Syd waits for Nadia, who has stolen a key from one of the scientists.

Later, Nadia spots Cesar Martinez. Nadia again flashes back to her teenage years. She's crying in the corner of a jail cell. Roberto Fox recruits her to work in espionage for the government. Nadia consults the headmistress of the orphanage, who encourages her to take the job. At the party, gunmen open fire as Martinez follows Sydney's path.

In the lab, Syd cracks the safe and retrieves the Amplifying Glass. When Martinez and his thugs enter, Syd surrenders the Glass. Martinez asks Sydney who she works for. Nadia arrives and says, "She works with me." He spares their lives.

Back at APO, Sloane reprimands Nadia for not sharing her past regarding Martinez. Nadia insists she can get the Glass back from Martinez. She doesn't tell them that she actually worked with Martinez under Roberto's tutelage.

In Buenos Aires, Nadia sits at an outdoor restaurant while Sydney and Weiss observe from a van. Martinez arrives and agrees to sell the Glass to Nadia on the condition that she accompany him back to his office without backup. Nadia agrees despite Syd's reservations.

Martinez asks Nadia if she still thinks about Roberto Fox. Nadia recalls finding her dying partner, who says that Roberto Fox is a criminal who had them steal government intelligence. Nadia thought she'd been working for the Argentine government.

Nadia admits to killing Fox and says she'd do it again. Martinez levels a gun at her. She hits him and turns the table, now aiming it at him. Sydney arrives with Weiss. Nadia tells them that the Amplifying Glass is in the safe and Weiss takes Martinez away. Sydney and Nadia embrace.

In Lisbon, Vaughn rings the door of the address mentioned in his father's journal. The door opens to reveal Nadia's headmistress at the orphanage! She says the only time she met Vaughn's father was when he came to her, covered in blood with a baby in his arms -- the baby was Nadia. Pressed for further details the headmistress says she heard his father mention one particular word during a phone conversation -- "Nightingale."

Season 4: Episode 13 - "Tuesday"

At an upscale nightclub in Havana, Cuba, Sydney invites a man to dance. It's her informant, and he tells her that the Third Faction is planning a large-scale attack on a civilian target. He also tells Sydney where a hard drive containing more information could be found, which Dixon soon retrieves. They're being watched, however.

As Syd travels to the airport, Vaughn, over the phone, promises her a slow dance. Suddenly, attackers shoot Syd's driver and the car crashes.

Dixon arrives at APO with the hard drive. Since Marshall is late, another agent is tasked with the decryption. When the drive is plugged in it sprays a toxin in the office, causing Dixon to go into a seizure. He's given an antidote and the office is locked down.

As Marshall arrives in the parking lot, he phones Sloane to tell him that the firewall networks are still secure. Sloane asks Marshall to stay on the line as they contact Sydney.

The ringing phone wakes Syd. To her horror, she realizes she's been buried alive, the dead informant beside her. Jack advises her to stay calm -- but that help won't be coming for the next 36 hours while the office is locked down. Marshall volunteers to go to Cuba and track Sydney's cell phone with a Radio Frequency locator.

While Dixon recuperates, Sloane tells the rest of the team that the Third Faction has enough toxin to infect an entire city. Despite their predicament, they must still discover the target city and prevent the Cyclosarin bomb from detonating.

Marshall arrives in Havana and creates his makeshift RF Locator. Sydney takes a photo of the dead informant and sends it through her phone to APO. Using the picture, the team links the dead man to Ulrich Kottor, a significant figure in the Third Faction, and the man who kidnapped Syd.

Syd's phone dies as Marshall arrives at the cemetery. Marshall realizes there are too many fresh graves for him to search. He asks Vaughn to direct a satellite over his position and change the view to thermal, figuring it will pick up Syd's body heat.

Marshall digs frantically, finally opening the coffin and finding Sydney unconscious. He performs CPR. After a few tense moments, she opens her eyes. An exhausted Marshall drops to the ground.

In the office, Sloane reports that they have acquired information about Ulrich. Since an attack is imminent, Sydney needs to get to Ulrich, find his hard drive and upload the contents to APO so they can stop the detonation. Sydney responds by saying that Ulrich knows her from Havana, and that they need to send someone else in: Marshall.

Syd advises Marshall on the spy game. Marshall, assuming an intimidating pose as Jack Bristow, walks inside Ulrich's private room and commands his attention. He tells Ulrich that one of his men is betraying him. As his "cigarette case" scans Ulrich's laptop, Vaughn reports from APO that they still can't access the data, and that Marshall must go to the basement with Ulrich in order to force him to shut down the network firewall. As Marshall tries to subtly assemble the gun he brought, he accidentally shoots and kills Ulrich. He calls Syd for help.

From the APO office, Jack instructs Marshall to dig out one of Ulrich's eyes. Sydney arrives and, using the eye, they bypass the retinal scan in the basement security system. Marshall then starts downloading from the hard drive and transmits intel to APO while Syd covers him. Later, Sloane reports that the Ministry of Security confirmed the seizure of the Cyclosarin bomb in downtown Hong Kong.

Sydney drops Marshall off at his house and he invites her in for dinner. A grateful Sydney refuses, saying that she needs to go the train station. At the station, Vaughn arrives. They slow dance in the middle of the train station, blissfully unaware of the bustling world around them.

Season 4: Episode 14 - "Nightingale"

Vaughn wakes up from a nightmare. Troubled, he tells Sydney that they should stop pursuing his father's past. Syd insists that they continue.

In a Siberian nuclear facility, two men lock an unconscious prisoner into a test chamber, while a scientist observes behind glass. When the prisoner wakes up, he realizes that he's the subject of a gruesome experiment. His flesh melts and he dies screaming.

Jack agrees to Syd's request for clearance on files relating to Vaughn's father. Starting with one word - Nightingale - from Bill Vaughn's journal, Syd discovers its connection to Dr. Josef Vlachko. She also finds that he's currently working with Hans Dietrich, a money launderer involved in weapons sales who funneled over a million euros to an account labeled Nightingale. Syd presses on with the search.

A wary Sloane asks Jack how much Sydney and Vaughn know about Project Nightingale. Jack suggests that they tacitly let the pair continue the search.

In a rogue operation, Syd and Vaughn go to Dietrich's beer hall in Munich. Dressed as a beer maid, Sydney charms Dietrich. Then they go back to his private office where she beats him and rips out the hard drive from his computer. As guards arrive, Syd and Vaughn fight their way out.

Back in Los Angeles, Vaughn secretly meets with a mysterious man named Roberts, who knows about their "trip" to Munich. Roberts says he'll give Vaughn info about his father in exchange for the transformer coil from Project Nightingale. Vaughn agrees, though he doesn't yet know what Nightingale is. Before he leaves, Roberts gives him his contact information and the name "Philip Burke" as a lead.

Jack invites Sydney out for dinner to learn more about their acquired intel. Sydney says that Vlachko is running Project Nightingale in an abandoned nuclear plant and using humans as test subjects for experiments. Jack tries to convince Sydney to bring this intel to APO.

Sloane tells Jack that due to Vlachko's ties with Elena Derevko, he needs to send a strike team to Siberia. Jack says they should wait for Sydney to willfully bring this to APO. Once she does, Jack will join the mission so he can interrogate Vlachko without Syd and Vaughn's knowledge. Sloane advises Jack to eliminate Vlachko because he can alert Elena about their agenda-or worse, talk to Sydney.

Vaughn tells Sydney about Philip Burke: he was killed the same day that Bill Vaughn was supposedly killed, and his dental records are identical to Bill Vaughn's. Vaughn also says that he met with Roberts, who wants the transformer coil. Syd suggests they bring this operation to APO, then acquire the coil through a rogue countermission. After they report to APO, Jack says that he'll join them in the retrieval of the transformer coil.

After infiltrating the Siberian nuclear facility, Jack shuts down security while Vaughn and Sydney run toward the test chamber. Sydney enters the chamber to retrieve the coil inside the nuclear reactor's containment shield. A guard arrives and shoots at Vaughn, destroying the control panel in the process. Syd is trapped inside as the nuclear reactor starts counting down. After Vaughn's failed attempts to stop the reactor, Marshall says another way to stop this is through the removal of fuel rods from the core.

Meanwhile, Jack finds and interrogates Vlachko. Upon hearing that Sydney's life is in danger, Jack shoots Vlahcko and heads toward the nuclear core to remove the fuel rods. Marshall advises Jack against this as he tries his best to bypass the system.

Suddenly, the nuclear reactor shuts down. Syd walks out the chamber and hands the coil to Vaughn. After they kiss, Vaughn punches Sydney and runs away with the coil as Syd watches him go. Sydney then goes to Jack and tells him that Vaughn took the coil from her.

Jack and Sloane discuss Sydney and Vaughn's deceit. Later, Marshall realizes that Jack shut down the reactor himself. Jack tells Marshall that his daughter's life depended on it and demands that his actions remain a secret.

Season 4: Episode 15 - "Pandora"

Dixon is shot by a masked gunman. The shooter approaches and takes off his mask, revealing … Vaughn.

Two days earlier, Vaughn meets a man named Roberts in a Paris cafe. Vaughn tells him that Roberts' employer will only get the transformer coil if they give more information about Bill Vaughn first. Roberts calls his employer and has him speak to Vaughn. The voice says that since Vaughn didn't follow their agreement, he must first complete an assignment. As instructed, Vaughn reaches under their table and opens an envelope containing surveillance pictures of Bill Vaughn, who, the voice confirms, is very much alive.

At a federal prison, Nadia visits Katya Derevko, who fondly recalls her childhood with Irina. Nadia refuses to talk about Syd, although Katya desperately wants to see her.

Concerned about Jack's exposure to radiation in the last mission, Marshall secretly uses the oil from Jack's fingerprints to create a sample that he sends to forensics for analysis. Later, Marshall learns that the results show a large-scale genetic mutation. He begs Jack to see a doctor.

Vaughn meets with a group of freelancers hired for the assignment. Roberts announces that they must steal a valuable item from an armored van - but first, they need a cold laser stored in a private hospital at Bordeaux. Vaughn and a team member infiltrate the hospital, first disguised as a couple needing medical attention, then as a doctor and a nurse. They successfully steal the laser.

After Nadia confesses to Sydney that she's been visiting Katya to learn more about Irina, Syd warns Nadia and reveals that Irina had hired an assassin to kill her. An angry Syd storms off to see Katya in the hospital.

Syd tells Katya to stay away from Nadia. Katya says that she would never harm Syd, nor would Irina. Before her death, Katya says, Irina believed that someone was setting her up to make it appear that she was trying to have Sydney killed. Katya gives Syd a lead.

Roberts briefs his team about their assignment: stealing a Rimbaldi manuscript from a CIA convoy. An angry Vaughn confronts Roberts, declaring that he can't betray his agency, and that if he did this, he can't go back. Roberts responds by saying "like father like son," and that his father was a bad guy himself.

Following Katya's suggestion, Syd goes to a repair shop and brings home a music box. Syd realizes that the box's flashing lights project a set of numbers, which Sydney researches in the CIA files. It leads to bank records containing payments to Syd's would-be assassin - whose source has the name "A. Sloane." Since it exonerates Irina, Syd shares this with Katya.

Vaughn and his partner infiltrate an armored van in the CIA convoy by burning a hole through the floor. Using the cold laser, they bypass security and secure the artifact. Vaughn runs out with his partner - but Dixon, who is part of the CIA convoy, chases them through a tunnel. Vaughn's partner shoots Dixon and Dixon fires back. Instinctively, Vaughn shoots Dixon. As Dixon slumps to the ground, Vaughn peels off his mask, realizing what he's done.

Vaughn meets Roberts at a warehouse and beats him silly. He demands the truth. Roberts admits that Bill Vaughn is dead, and that the journals and pictures were a set up. He says that he works for Sloane.

Vaughn arrives at Syd's apartment and they embrace. Vaughn says his father had been dead all along, and that he realized that the father he knew would never have walked away from the people he loved. Vaughn tells Sydney that Sloane was behind this.

In Santiago, Chile, a frustrated agent reports to his boss that Roberts failed and the manuscript has not been recovered - he calls his boss "Mr. Sloane." This Sloane, who resembles Arvin Sloane, tells him that everything should proceed as planned.

Season 4: Episode 16 - "Another Mr. Sloane"

In Krakow, Poland, men posing as airport guards abduct Professor Sinclair, a nuclear physicist. She wakes up bound in a dark room and is greeted by Arvin Sloane. Actually, it's not Sloane but an impersonator.

Sydney and Vaughn meet with Jack. They tell him about the elaborate conspiracy behind Vaughn's search for his father. Syd adds that she also believes that Sloane was behind the recent attempt on her life. When Syd suggests they notify the agency, Jack says he will handle it.

Jack corners Sloane, who calmly denies his involvement and points out his lack of motive. They conclude that someone is setting Sloane up.

The Sloane impersonator (Sloane 2) shows a Rambaldi manuscript to Sinclair, saying that he needs her expertise. Sinclair says that she needs a transformer coil for this experiment to work and Sloane 2 tells her that she needs to find another way. He has his man Carter torture her.

In the APO office, Jack tells Syd and Vaughn that Sloane is not behind these conspiracies. They then use a handcuffed Roberts to confirm that APO's Sloane is not the man who hired him. Sloane orders the team to find the phony and they persuade Roberts to meet with Carter about the transformer coil.

With the APO team undercover, Roberts walks in a hotel lobby carrying the transformer coil in a secure case. Vaughn tells Roberts that when Carter comes, they'll move in and make the arrest. A man approaches Roberts, saying he's there to make the swap - but the exchange should take place in the penthouse. Though concerned that it wasn't Carter, Roberts complies.

As Roberts rides a glass elevator up to the penthouse, Syd sees Sloane 2 on his way down in another elevator. She reports it to Sloane, who predicts that Sloane 2 will cut the cable. As soon as he says this, Roberts' elevator crashes to the ground. Carter retrieves the coil, which he hands to Sloane 2.

At the APO office, Sloane suggests excusing himself from this mission since it concerns his past obsession, Syd urges him to stay so they can anticipate Sloane 2's next move.

After leafing through a Rambaldi manuscript under close surveillance, Sloane tells the team that Sloane 2 is constructing an energy source that requires the transformer coil. To do it, a nuclear physicist specializing in quantum electrodynamics is needed, and Jack adds that Dr. Sinclair, who fits the bill, disappeared last week. Sloane further states that the experiment needs Zanthium 242 to be successful. He calls a Sicilian contact who trades illicit chemicals and confirms that an "Arvin Sloane" ordered a large amount of Zanthium, to be shipped the next morning. Sloane travels to Sicily to intercept the shipment and find out where it's headed.

Disguised as delivery agents, Sloane and the team arrive at Sloane 2's facility in Chile. The team splits up with Sydney and Sloane going to the lab; while Vaughn, Weiss and Nadia attempt to rescue Sinclair.

Sloane helps Sydney break into the lab, where they recognize the Rambaldi energy source, a rotating red ball hovering over magnets. Just then, Vaughn radios to say that Sloane 2 and his henchmen escaped with Sinclair and are heading her way.

Sydney battles the thugs as Sinclair hides and Sloane 2 escapes. Carter arrives at the lab and mistakes the real Sloane for his employer. Sloane shoots him in the kneecap and demands to know what's going on. Carter babbles about immortality, to which Sloane replies that Rambaldi's secrets would never be revealed to such a fool. Sloane beats him silly.

Nadia arrives at the lab, sees the Rambaldi experiment before her. She also sees the darker side of Sloane - enraged and blood-spattered. He turns to Nadia and says quietly, "It's all over now."

Season 4: Episode 17 - "A Clean Conscience"

The APO team watches footage of an explosion at the Indonesian embassy in Copenhagen that killed 15 people, the work of terrorists headed by Milos Kradic. Sloane says that an agent named Thomas Raimes is undercover within the organization. Although Raimes warned Langley of the attack, he failed to prevent the blast or follow up with his handler. They speculate that Raimes might have been caught or killed.

Sloane tasks Dixon and Vaughn with capturing Kradic. He asks Sydney and Jack to run operations, though they have yet to find out Kradic's motives.

Sophia, the headmistress who took care of Nadia in the orphanage, phones to say she's coming to L.A. When Syd and Nadia meet her at the airport, she's wheelchair-bound and covered with bruises.

Sophia tells Nadia that she was attacked in her home and doesn't know why. Sloane comforts her, clasping her hand. Later, he peels off a thin layer of latex from his own hand and has Marshall check Sophia's fingerprints. Sophia gives Nadia a necklace reminding her of their past.

Jack receives treatment for his radiation poisoning. His doctor, Atticus Liddell, warns him of side effects and advises him to make peace with Syd - because the end may not be far off.

In Amsterdam, Dixon tells Vaughn that he's previously worked with Raimes. They corner Raimes in a club and ask why he didn't stop the bombing. Raimes says that the 15 civilian deaths were necessary in order to find out what Kradic wanted -- Hydrosek, a water-based weapon developed by Indonesia that could wipe out entire eco-systems and kill half a million people.

Dixon and Vaughn inform APO that Kradic bombed the embassy as cover for the intel theft. Since embassy protocol dictates that when a bomb goes off, all confidential intelligence goes to offsite servers, the recent explosion triggered these protocols. APO concludes that Kradic must've intercepted the outgoing data, which includes the location of Hydrosek, and he is now forming a team to steal it from Indonesians.

Raimes says their only option is to make Kradic lead them to the weapon. Dixon agrees, and when Raimes says that Kradic is about to meet Halsey, a hacker he's hiring for the first time, Dixon suggests switching the hacker with an agent. After they nab Halsey, Dixon approaches Kradic in the club and convinces him that he's the hacker.

Sloane approaches Sophia and demands to know why she really came. He says that he knows about the man she killed. Sophia says the man was a danger to the girls in the orphanage. She also adds that she wanted to protect Nadia, so she changed Nadia's last name -and that her attackers in Lisbon were really after this information. Sloane reveals that he knows who's after her.

In the office, Jack tells Sydney that the embassy transmission Kradic had intercepted came from a network tap that they can still access. When Syd leaves the room to look for Marshall, Jack scratches and probes his palm and finds a computer chip stored in an embedded capsule.

Jack sees Dr. Liddell who tells him that this device regulates his medication, and that the procedure was explained to him. As Jack says he cannot recall this, the doctor reminds him that memory loss is a side effect and admits that Jack's condition is progressing quicker than expected.

Syd reports that Marshall located Hydrosek in a manufacturing plant in Peru. Unfortunately, Kradic beat them to it. They decide that the best course of action is to keep Dixon in play.

Dixon tells Raimes that the embassy deaths were unacceptable. When Raimes says that they were collateral damage and that Dixon has gotten soft, Dixon explains that his wife was accidentally killed during a mission.

As Kradic, his team, Raimes and Dixon approach a plane, one of Kradic's men intercepts a communication from a lurker with Coke-bottle glasses, regarding Dixon's embedded status. Knowing now that one of them is an agent, he orders his men to kill them both.

Raimes punches a thug, grabs a gun and shoots the others as he's wounded. Dixon, still keeping his cover, pretends to turn against Raimes - who is sacrificing himself for the mission to continue. Knowing that Vaughn is on standby to save Raimes, Dixon shoots Raimes and boards the plane with Kradic.

Jack takes Sydney in a room with Sloane and Nadia, and the men tell their daughters about info they've gathered about Elena Derevko. Elena disappeared 30 years ago, Sloane says, and she has been surveilling them for a decade. In fact, she might be responsible for the attack on Sophia. Her motives and location are unknown but they're doing everything they can to find out.

Unbeknownst to Nadia, the necklace she's wearing - the gift from Sophia -- transmits this conversation to … Sophia. She contacts Coke-bottle glasses and tells him that she'll contact him once she has Kradic's final destination. He responds by saying, "I won't let you down, Elena."

Season 4: Episode 18 - "Mirage"

Posing as a waitress at a Vienna club, Sydney serves drinks to Kradic's crew, which includes an undercover Dixon. Syd reports to APO that she overheard Kradic tell Dixon that the Hydrosek will arrive soon. Sloane realizes that Jack did not arrive that morning.

The lurker - call him Coke-Bottle Glasses - has followed Kradic from Amsterdam and begins planting explosives in the club. Vaughn, observing by the bar, sees two suited men carrying a briefcase containing the Hydrosek.

Coke-Bottle Glasses (CBG) puts a glass down on Sydney's tray. Realizing that it's a bomb, she throws it to an empty corner, where it explodes. CBG detonates another bomb and, as the crowd panics, he grabs the briefcase and heads toward the exit.
Syd tackles CBG and they exchange blows as the Hydrosek case skids across the floor. He escapes. Dixon shoots a thug about to kill Vaughn as he goes after the briefcase. Kradic gets to the briefcase first and runs.

Dixon and Vaughn follow Kradic into the basement. Cornered, Kradic threatens to drop the Hydrosek in the filtration grate of the city's drinking water. Dixon pretends to lower his gun, then shoots Kradic.

After learning of CBG's failure to steal the Hydrosek, Sophia invites Nadia and Weiss over for dinner. Upon their arrival, Sophia takes Nadia's belongings - which include a laptop - to a back room. CBG emerges from the shadows and hacks into the laptop, gaining access to APO files.

At APO, Syd tells Vaughn that she hasn't seen her father in two days. They go to his apartment and find a notebook with recent records of Jack's vitals. Inside the bathroom, they find containers of medication and blood-soaked bandages in the trash can.

Jack visits Dr. Liddell, who says that years ago during an experiment he discovered that a lethal dose of an alkylating agent cured a few genetically mutated rats --but 84 percent died. Despite Dr. Liddell's warnings, Jack acquires the lethal chemical.

Based on the meds she saw at Jack's place, Syd asks Marshall to research cures for radiation sickness. Marshall reveals that Jack got sick when he removed the fuel rods in a radioactive lab in order to save Sydney. Marshall adds that there is no cure.

Sloane tells the team that Jack needs help and Syd adds no area hospitals have any record of his admittance. She says Jack's mental capabilities might be impaired at the moment and someone might be preying on him, promising a cure.

Jack returns to Liddell's office. Meanwhile, the APO team locates Jack's car in a seedy neighborhood. Syd and Vaughn drive to the location and arrive at an abandoned building, where they find Jack on a bed in the middle of a big empty room. He injects himself and begins convulsing.

At the APO office, Vaughn explains to Sloane that Jack thought he had a cure, and unfortunately, Jack's condition is irreversible after 72 hours. Vaughn also mentions that Jack has been suffering from hallucinations and woke up briefly to look for a "Dr. Liddell." Sloane tells the team that 25 years ago, Liddell developed a thesis on the treatment of genetic mutations. He went to the Soviet Union in 1981 to spy for the US. When his cover was blown, Jack's extracted him and gave him a new identity. Only Jack knows where Liddell is.

Jack wakes up and talks to Sydney, referring to her as "Laura," Irina's cover name. Sloane suggests using these hallucinations to convince Jack that he's living in '81 -- specifically, the day he extracted Liddell from Russia. He proposes recreating Jack's surroundings to guide his delusions and make him reveal where the actual Liddell is located.

Looking like Irina, Sydney enters a room built to resemble her old house. As the team observes, Jack responds to the scenario. Vaughn calls, pretending to be Jack's handler, and asks what arrangements he needs to make for Liddell. Jack reveals where Liddell should go -- in code.

Believing that Syd is his wife, Jack tells her that he needs to leave town and help Liddell get a new identity in Finland. Jack continues on about his deep regret of missing Sydney's birthday and his lack of involvement in her life. Syd listens, deeply touched.

Marshall asks Nadia why she requested that the Hydrosek be moved. Realizing that someone has hacked into the system, Nadia and Weiss go to the facility where the Hydrosek is stored and find that it's been stolen. CBG lies dead in front of the vault.

Syd finds Dr. Liddell in Helsinki. He accompanies her back to APO and sees Jack, who asks if he's cured yet. Liddell answers, "Not yet… but I'm going to make you better."

Season 4: Episode 19 - "In Dreams"

Sloane's impostor (Sloane 2) arrives at an Italian monastery to discuss with Father Kampinski his experiments on breeding the aggression out of bees. As Kampinski shows him a supposedly extinct orchid mentioned in Rambaldi's Vespertine papers, Sloane 2 offers 50 million dollars in exchange for a cutting and the text. Denied, Sloane 2 has an accomplice trigger Rambaldi's Mueller Device, which causes the bees to attack and sting the monks to death.

Sloane informs the team of the orchid theft and orders them to recover the orchid and find the impostor. Marshall says that this orchid has properties that heighten receptivity. Privately, Jack confronts Sloane, blaming him for this predicament.

The team sets a trap for Sloane 2, bringing him out by pretending to put the Vespertine text up for auction in Paris. Via surveillance, Dixon and Vaughn chase a man attempting to steal the papers. They stop a delivery truck. In the back, they find Sloane 2.

During questioning, Sloane 2 invites Syd to work with him. He proposes eliminating the world's bad guys and fostering harmonic coexistence by administering the orchid extract to the general population via drinking water.

Marshall points out that Sloane 2's brain patterns are identical to Sloane. He also recalls working on an SD-6 program for brain imprinting that Jack says was run by Calvin McCullough, a senior partner in SD-6. Project Brainstorm's purpose was to explore experimental technologies for interrogation, brainwashing and transferring memories. They conclude that finding McCullough will lead them to the orchid.

Vaughn and Dixon approach McCullough in Buenos Aires. He admits that he made Sloane 2 believe that he is Arvin Sloane, but that Sloane 2 double-crossed him and kept the orchid for himself. As he calmly adds a packet of cyanide to his coffee, he declares that his employer wouldn't let him be interrogated. He drinks up and dies.

Sloane confesses that through Omnifam he contaminated the drinking water of 400 million people worldwide as the first phase of creating a more peaceful species of human. The second phase, based on Rambaldi's teachings, was to introduce the orchid's nectar into the water supply. But without the orchid, Sloane's attempts at duplicating the formula failed. Now that Sloane 2 has the orchid, however, he has only to drop the nectar into the water supply to bring the affected people under his control.

Marshall tells the team that Sloane 2 was created from Sloane's own brain scans. He postulates that the Sloane clone won't reveal the orchid's location unless he stops believing that he's Arvin Sloane. The only way to do this, he says, is to shock Sloane's personality out of him using a traumatic memory. In order to present the most vivid memory, Sloane must relive the past.

Jack hypnotizes Sloane and guides him through his memory. Sloane's sees his pregnant wife Emily and they decide that their daughter will be named Jacquelyn. They are devastated when Jacquelyn dies shortly after birth.

They upload this painful memory to Sloane 2, who suddenly reveals that he's a prisoner of war named Ned Bolger. He says that the orchid is located in Switzerland. Shortly thereafter, he switches back to the Sloane 2 personality and breaks down.

Sloane refuses to wake up, preferring to alter his memory and live on happily with Emily and a healthy Jacquelyn. Forcing him awake, Marshall says, may kill him. Nadia nonetheless wants to get him back. She gently tells Sloane that he can't stay in his dream because his must undo what he's set in motion. When Sloane admits that he's ashamed of his past, Nadia says she believes that he can redeem himself.

Sloane awakens and Nadia embraces him. Alone with Jack, Sloane reveals that Rambaldi meant nothing to him until after Jacquelyn died, when he used the writings to fill the hole in his heart. Seeing Ned showed him how much of himself he had lost. He promises to rectify his misdeeds, though every day is a struggle.

Season 4: Episode 20 - "The Descent"

A tactical group infiltrates the DSR and steals the Rambaldi artifacts. Meanwhile, Sophia says goodbye to Nadia and Sydney, telling them that the Lisbon police confirmed that it is safe for her to go back home.

In the APO office, Vaughn plans to propose to Sydney and asks for Jack's blessing. As Jack begins to express his disapproval, a team of CIA agents arrive in the office with a search warrant.

Director Chase looks for Nadia in Syd's apartment. When Nadia confirms that she is the only one who has access to her laptop, Chase accuses her of overwriting the DSR security system by deactivating the alarms. Just then, an agent finds the bugged necklace that Sophia gave to Nadia.

Jack and Sloane arrive at the apartment. They then realize that Sophia must be the reason why several missions have been compromised. Jack postulates that Sophia is Elena Derevko, who unfortunately, had found them first. He points out that the string of orchestrated events -- Bill Vaughn's journal and Sloane's clone -- were her handiwork. Sloane adds that they can't let her assemble the Rambaldi artifacts. Later, Sloane tells Nadia that Elena will go to Lazlo Drake with the Rambaldi pieces.

Nadia flashes back to a year earlier in China, where she and Sloane met Drake. Sloane explains that Drake discovered a manuscript - a template describing how Rambaldi's artifacts should be assembled, bringing forth the final prophecy. Drake is taken with Nadia, but he refuses to share information since Sloane is still missing one artifact: the Sphere of Life. He says that Nadia is the only one who can retrieve the Sphere.

They then go to an underground cave in Sienna, where Sloane asks Nadia to obtain the Sphere in a box perched on a podium that is surrounded by stained glass floors. Nadia carefully walks on the creaking glass and opens the box. As she touches the Sphere, she sees a vision of destruction and refuses to bring the Sphere to her father. Sloane calls her a coward and attempts to walk across the glass floor by himself. The floor shatters and he falls through, impaling him. Nadia nurses him back to health.

In the present, Sloane tells the team about Drake and adds that in Elena's hands, Rambaldi's endgame is apocalypse. They attempt to locate Drake, who has been in hiding with the aid of Grayson Wells - a billionaire who financed Drake's earlier Rambaldi research. Sloane tasks the team to approach Wells, and says he will talk to Drake himself.

At Cannes, Sydney poses as a spoiled heiress in a jewelry store and brushes past Wells. She pretends to purchase a bracelet and charms Wells into putting it on her wrist. As Wells sees a Rambaldi mark on Sydney's hand similar to his, he offers to buy the bracelet for her. Later, Wells now tied to a chair, Sydney phones Sloane with the location.

Syd meets Sloane in Mexico. When she expresses her suspicions, Sloane tells her that he would never do anything to hurt Nadia. They approach a trailer; Drake lies dead inside. Syd finds a surveillance video recorded from a hidden camera, revealing Elena chatting with Drake. Before Sydney can listen to their conversation, Sloane stabs her with a tranquilizer and heads out to Elena's office.

Jack arrives in Katya's jail cell and demands to know Elena's operations. In response, Katya asks for a full pardon and immediate release. When Jack says he'll do everything he can, Katya reveals that Elena has been acquiring artifacts for several years through her front -- The Covenant. Katya says she can help him find her, but it is only Irina who can stop Elena from acting on her end game. Jack, if you recall, murdered Irina.

Finding out that Elena is in an industrial facility in Prague, Syd, Nadia and Dixon prepare to infiltrate. Dixon arrives at a loading dock and watches the guards put a prisoner in the van. Sloane emerges from the shadows and points a gun at Dixon. He asks for Dixon's trust and tells him to get out of there. Suddenly, Dixon is shot from behind by Elena and Sloane looks at Dixon regretfully before leaving.

At the hospital, Syd and Jack observe as Director Chase cares for Dixon. Jack admits that he lost sight of the one thing he knew to be true -- that Sydney's mother, Irina, would never hurt Sydney.

Jack crosses paths with Vaughn in an elevator. He says that if Vaughn honestly believes that he can make Sydney happy, then Vaughn has his blessing.

Dixon regains consciousness and talks to Nadia and Sydney. He tells them that he saw a shackled prisoner at the loading dock: Irina Derevko.

 Season 4: Episode 21 - "Search and Rescue"

Jack regretfully recalls the time he shot Irina in Vienna, under the belief that she was responsible for putting a hit on Sydney. Syd arrives in the office and tells Jack that Dixon, who claims that he saw Irina, could be delusional. Jack says that he killed a woman he believed to be Irina, and reminds Sydney of the doubling technology of the Helix Protocol.

Marshall bursts into Jack's office and reports that they found Elena's associate, Lucien Nisard, who worked with The Covenant. Jack tells Marshall to check the Blackwell Index via Sloane's computer.

Suddenly, TV screens in the APO office display news reports about Sovogda, a Russian city in chaos. Marshall then receives a video feed from a hacker in Moscow, showing raw footage of anarchy. The footage reveals a giant red ball hovering in the sky - Rambaldi's Mueller Device.

The team believes that Sloane and Elena have activated the Rambaldi device in Sovogda, which resulted in unbridled aggression in its citizens. They conclude that the city's contaminated water supply combined with the chemical properties of the orchid made the residents susceptible to the Mueller device. The only solution is to disarm the device properly -- and Irina Derevko, who is being held prisoner by her sister, is the only one who can do it. They need to force Lucien Nisard to reveal her location.

Vaughn comforts Sydney and tells her that they're going to get through this. As he was about to bring out the ring and propose, Marshall arrives and says that it's time to leave.

They arrive at a dance club in Ibiza, where Sydney goes in with Vaughn and spots Nisard. Syd and Vaughn make out -- and as Syd makes eye contact with Nisard, she invites him to join them. They go to the bathroom where Sydney and Vaughn transmit his PDA contents to Marshall. When they find that the Helix Protocol is mentioned, Syd dunks his head in the toilet and asks about Irina. Nisard confesses that Elena doubled Irina and confirms that the real Irina Derevko is in Guatemala.

When Syd and Nadia arrive in Tikal, Guatemala, Jack guides them via a satellite layout of the camp until they locate an underground cell. They open the hatch, finding Irina.

"I knew you'd come," Irina tells Sydney, and they escape. As guards chase them, Sydney walks into a trap and is strung upside-down. Irina rescues Sydney while Nadia holds the guards off. They run to escape as more guards arrive. Syd throws a grenade at them and, along with Irina and Nadia, escapes on a raft.

On the plane, they tell Irina that Elena and Sloane have enacted their plan. Irina shares that she found a Rambaldi manuscript - Il Diluvio - which revealed Rambaldi's desire for a complete cleansing through apocalypse. Though Irina destroyed the manuscript, Elena tortured her to get the info, forcing her into dozens of cardiac arrests. Irina admits that she finally broke and told Elena everything. Now, they must go to Sovogda and stop them before they move to another city.

Irina breaks down when she realizes who Nadia is. Later, as they look over a map, they agree that Sloane and Elena must be somewhere in Sovogda but safe from the Mueller device. Suddenly, Jack gets a call from the pilot, and their plane is diverted by official orders from Langley.

As they land, police cars arrive and arrest Irina, who is still a fugitive. Syd goes to Director Chase and argues that Irina is the only one who can help them. Chase says the matter will be resolved in a few hours by a Russian air strike. Syd points out that this will release toxins in the atmosphere and results will be catastrophic. She begs Chase to trust her.

As the team prepares to parachute into Sovogda, Vaughn pulls Sydney aside and says that he wants to spend the rest of his life with her. He gives her the ring and asks her to marry him. Overwhelmed and delighted, Sydney kisses him and tells him to ask her again on the beach.

The plane's rear door opens and Irina, Jack, Vaughn, Nadia and Sydney jump out.

Season 4: Episode 22 - "Before the Flood

Jack, Irina, Nadia, Vaughn and Sydney land in the city of Sovogda. They walk through a deserted street littered with corpses and burning cars. As they wait for the Department of Special Research team, they speak to Marshall and Weiss, who report that Director Chase is trying to convince the Russians to call off the air strike.

At APO, Marshall and Weiss use the Blackwell Index to blackmail a Russian minister into giving them the access code to a Russian satellite. They soon discover that Elena is uplinking to the Russian network.

Syd follows a DSR signal, which leads to a severed arm. Suddenly, a CIA agent named Brodien emerges from the shadows and tells them that his DSR team was ambushed by the infected mob, which has left thousands dead. He reminds them that the Rambaldi device is broadcasting a subaudible frequency that physiologically alters people who drink the water. The symptoms, he says, are irreversible.

He also says the epicenter is located over the Oransky building, and that while he has taken out the city's power grid, the device is still running. Irina suggests that it has been modified to run using an internal energy source. They decide to take the subway, as it is the quickest way to the building.

Elena learns of the APO team's arrival. When Sloane volunteers to lead the assault team, Elena tells him to bring Nadia back and give her the option to join them.

As the APO team approaches the subway tunnel, an infected man impales Brodien with a rod. As Jack, Vaughn and Irina try to start the train's emergency battery system, Syd and Nadia go inside the train's switching room to force the train to stop at the Oransky building. Irina urges Vaughn to tell Syd "the truth." Syd tells Nadia that Vaughn asked her to marry him. Nadia and Sydney split up to manually adjust the switches.

Sydney returns to the train first while Nadia, down the tracks, flips the switch. The train rolls down the tracks as a mob chases Nadia. Jack refuses to stop the train because if he does, it won't start again. Sydney stretches to pull Nadia to the train but she's tackled by an infected madman. Irina tells Syd that Nadia is still alive.

Sloane kills Elena's men and waits at the station. He tells them that Elena has primed the world's drinking water. As Syd voices her suspicions, Sloane says he allied himself with Elena to put an end to this himself, but Elena built in a security device that Sloane couldn't crack. Jack punches Sloane and takes control of the team.

Marshall reports that Elena is going to use the Russian satellite to distribute the Rambaldi frequency worldwide. Once it goes online, the Rambaldi signal will be broadcast and everyone will be infected. Irina says they need to shut down the device from the roof of the building.

Jack tells Sloane to take them to Elena. Sloane cautions that once they disable the device, the toxins will dissipate in the atmosphere and the person who disarms it will only have a few seconds to run. When Irina insists that she can cut the wire and reverse ionization, Sloane reveals that Elena had changed the wiring scheme as a fail-safe. Irina orders him to take her to Elena so she can force her to reveal information while Syd disarms the bomb.

Nadia fends off the mob and wanders the streets. She approaches a wounded man who surprisingly holds a gun to her head and takes her to Elena. When she refuses to join Elena, Elena injects her with the contaminated water.

Before Syd heads out to the rooftop to disarm the bomb, she turns to Vaughn and says, "Just in case: yes, I'm gonna marry you." She wears his ring and hops into the elevator.

Marshall tries to connect to the satellite. Weiss says the President and his Cabinet are being evacuated to secret bunkers.

Sloane arrives with Vaughn, Irina and Jack. Vaughn searches for the relay room. They strap Elena to a chair.

Sydney reaches the rooftop and opens a hatch that revealed hundreds of interwoven wires. Nadia, now infected by the device, walks toward Sydney. Jack and Irina urge a reluctant Syd to take her out. The sisters battle. Vaughn blows the relay but nothing happens. Irina tells him to get to the roof. Sydney knocks Nadia out and chains her up.

Vaughn arrives on the roof and realizes that Sloane is not there. Meanwhile, Irina guides Sydney in disarming the device. Irina gives her sister a chance to help them as Jack gets ready to torture Elena. When Jack pierces her with a syringe, Elena yells that Sydney should cut the white wire. Irina shoots Elena in the head and tells Syd to cut the blue wire instead and run fast -- she only has 15 seconds.

Sydney is about to cut the wire when Nadia strangles her from behind with the chain. As Sydney starts to suffocate, Sloane arrives and shoots Nadia. Syd sees Vaughn and tells him to take the wounded Nadia with them. Syd then cuts the blue wire and runs away as the device starts to fall apart. They race inside the quaking building and sprints toward a shelter -- they have just saved the world.

Jack advises Irina, who is wanted by the CIA, to disappear. They kiss. Irina tells Syd that she's proud of her. She says that Syd may not see her on her wedding day, but she'll see Syd.

Later, Syd visits Sloane in a jail cell, tells him that Nadia is stable, but they're still trying to find an antidote. The Russian military executed all survivors to support their claim that it was a chemical explosion. Sydney has arranged for Sloane to see Nadia. She believes he was trying to do the right thing. Sloane thanks her.

Driving in Santa Barbara, Syd suggests to Vaughn that they blow off the big wedding and elope. After professing their love, Vaughn reveals that that he was a bad guy before they met. He continues to say that to begin with, his name is not Michael Vaughn. Before Sydney can react, a car collides with theirs.