Episode: 1x01 | Airdate: Sep 30, 2001
Sydney Bristow is a college student who leads a double life: she works for shadowy government agency called SD-6 which is supposed to be a covert branch of the CIA and reports to Arvin Sloan. Recently engaged, she tells her boyfriend, Danny Hecht, the truth. The next day, he is murdered. Later, Sydney's father, Jack Bristow, tells the truth: he is a double agent for the real CIA, as SD-6 is a renegade agency who allegedly killed Sydney's fiancé. Sydney must make a decision which will haunt her for the rest of her life. Sydney's partner in the field, Marcus Dixon, is also unaware about his true alliances as is SD-6's tech expert, the socially awkward Marshall Flinkman. Sydney's friends, the headstrong Francine, and the ambitious journalist Will Tippin are also unaware about Sydney's double life, until Will becomes inquisitive about Sydney's well-being following her fiancé's murder.
Episode: 1x02 | Airdate: Oct 7, 2001
In her new role as a double agent for the CIA, Sydney is intent on destroying SD-6 within weeks.
Episode: 1x03 | Airdate: Oct 14, 2001
Sydney and Dixon go to Madrid to steal a lockbox containing a sketch with what appears to be a digital code drawn by a 15th century seer, Milo Rambaldi.
Episode: 1x04 | Airdate: Oct 21, 2001
Sydney and Anna memorize a code written by Rambaldi. Sydney and Dixon are sent to investigate a plot to eliminate the United Commerce Organization.
Episode: 1x05 | Airdate: Oct 28, 2001
Will tells Francie that he's been investigating the death of Danny. Sydney learns from Vaughn that her father may also be working for the FBI.
Episode: 1x06 | Airdate: Nov 18, 2001
Sydney forms the opinion the Jack's suspicious activities led to the death of her mother 20 years earlier, creating a deeper tension between them.
Episode: 1x07 | Airdate: Nov 25, 2001
Sydney learns about the Shepard's involvement in her past. Sloane confronts the Alliance about the CIA bug, and they conclude that SD-6 has been moled.
Episode: 1x08 | Airdate: Dec 2, 2001
Sydney travels to Oxford to steal an ancient clock connected to the Rambaldi mystery.
Episode: 1x09 | Airdate: Dec 9, 2001
Sydney is scared, as she thinks that Dixon may have heard her talking to the CIA.
Episode: 1x10 | Airdate: Dec 16, 2001
Jack must save Sydney when Sloane orders her to be tortured and killed after she is suspected as the mole. Sydney tells Vaughn about her time at SD-6.
Episode: 1x11 | Airdate: Jan 6, 2002
After Jack saves Sydney during a mission, she discovers that he was responsible for the deaths of many CIA agents, complicating her feelings for him.
Episode: 1x12 | Airdate: Jan 20, 2002
A group of heavily-armed intruders sneak into SD-6 and take control of the building.
Episode: 1x13 | Airdate: Feb 10, 2002
Sydney discovers a note left for her by her father, explaining the dire predicament: opening the SD-6 vault would trigger a fatal explosion.
Episode: 1x14 | Airdate: Feb 24, 2002
Sydney and Dixon travel to Las Vegas to try and track down the group that nearly destroyed SD-6.
Episode: 1x15 | Airdate: Mar 3, 2002
Sydney and Dixon are dispatched to Tunisia. A Rambaldi manuscript is being held on a yacht, and their mission is to retrieve it before Sark gets it.
Episode: 1x16 | Airdate: Mar 10, 2002
The Department of Special Research inquires about Sydney's connection to the Rambaldi notebook.
Episode: 1x17 | Airdate: Mar 17, 2002
While being questioned by the FBI about her ties to Rambaldi, Sydney makes a shocking discovery that may unravel the mysterious 500-year-old prophecy.
Episode: 1x18 | Airdate: Apr 7, 2002
Sydney is reunited with Noah Hicks, an SD-6 agent she dated five years ago.
Episode: 1x19 | Airdate: Apr 14, 2002
Vaughn confirms that K-Directorate has hired an assassin, known as "The Snowman" for his favored use of an ice pick as a weapon, to take out Khasinau.
Episode: 1x20 | Airdate: Apr 21, 2002
Sydney and Vaughn meet with Mr Sark hoping to catch Khasinau, but Sydney's cover is endangered when an SD-6 agent is sent to stop the trade.
Episode: 1x21 | Airdate: May 5, 2002
Sydney and Dixon must go to a Paris nightclub, where Sark will deliver the ampule to Khasinau. Dixon is to steal pages of a Rambaldi manuscript.
Episode: 1x22 | Airdate: May 12, 2002
Vaughn and Sydney must destroy a Rambaldi artifact to save Will. Jack makes a deal with Mr Sark, and The Alliance decides the fate of Emily Sloane.
Episode: 2x01 | Airdate: Sep 29, 2002
Sydney finds herself face-to-face with her mother, Irina Derevko.
Episode: 2x02 | Airdate: Oct 6, 2002
Sydney begins to question whether her mother is trying to help her or trying to get her killed.
Episode: 2x03 | Airdate: Oct 13, 2002
Sydney must stay one step ahead of Mr Sark in retrieving a crucial piece of intel. Jack must face Sydney's mother while Will meets Vaughn.
Episode: 2x04 | Airdate: Oct 20, 2002
Sydney's dealings with her mother lead Jack to take drastic measures to ensure his daughter's safety. Meanwhile Will is confronted by a mysterious woman about resurrecting his story on SD-6.
Episode: 2x05 | Airdate: Nov 3, 2002
Sydney uncovers a chilling secret while on a case. Vaughn suspects Jack of setting up Sydney's mother to take the fall.
Episode: 2x06 | Airdate: Nov 10, 2002
Jack does what it takes to earn back Sydney's trust, while Sydney and Vaughn may have been exposed to a deadly virus.
Episode: 2x07 | Airdate: Nov 17, 2002
Sydney must make a deal with her nemesis, Mr Sark, in order to find a cure for an ailing Vaughn.
Episode: 2x08 | Airdate: Dec 1, 2002
The Bristow family goes undercover on a deadly mission and Mr Sark joins forces with SD-6.
Episode: 2x09 | Airdate: Dec 8, 2002
While continuing the first family mission together, Sydney and Jack learn where Irina's loyalties lie.
Episode: 2x10 | Airdate: Dec 15, 2002
Alliance counterintelligence head Ariana Kane is investigating the disappearance of Emily Sloane. Marshall is sent on his first mission.
Episode: 2x11 | Airdate: Jan 5, 2003
Marshall's life is placed in mortal danger. Ariana Kane has her sights set on Jack as the prime suspect in the disapearence of Sloane's wife.
Episode: 2x12 | Airdate: Jan 12, 2003
Ariana Kane tracks Sydney in order to catch Jack. Sydney and Vaughns covers may have been compromised after sharing a romantic dinner together in France.
Episode: 2x13 | Airdate: Jan 26, 2003
Sydney and Jack scramble to get information on the new Director of SD-6, who is appointed when Sloane goes missing.
Episode: 2x14 | Airdate: Feb 2, 2003
CIA Agent Lennox's identity is called into question by Sydney, Jack and Vaughn after his deep cover mission is blown.
Episode: 2x15 | Airdate: Feb 9, 2003
Sydney thinks about leaving the agency. Sloane kidnaps a scientist to help him piece together the mysterious Rambaldi device.
Episode: 2x16 | Airdate: Feb 23, 2003
Sloane discovers the powers of a mysterious Rambaldi device. Sydney senses that Francie is keeping secrets.
Episode: 2x17 | Airdate: Mar 2, 2003
Sydney begins to lose trust in Vaughn when she discovers the he is under investigation by the Agency.
Episode: 2x18 | Airdate: Mar 16, 2003
Sydney faces off with her mother, while Emily Sloane must decide whether to side with her husband or betray him.
Episode: 2x19 | Airdate: Mar 30, 2003
Sydney defies her father in her attempt to rescue a kidnapped scientist, while Sloane, seeking revenge, becomes more dangerous than ever. Meanwhile, Allison manipulates an unsuspecting Will for his agency connections.
Episode: 2x20 | Airdate: Apr 27, 2003
The Agency acts to stop an apocalyptic event prophesized by Rambaldi. Vaughn questions Dixon's state of mind.
Episode: 2x21 | Airdate: May 4, 2003
Sydney begins to question Will's identity when he's arrested for espionage, under suspicion of being a double. Meanwhile Sark and Irina plot to recover the Di Regno heart, and Sloane makes Jack a business proposal.
Episode: 2x22 | Airdate: May 4, 2003
Sydney confronts her mother, who reveals her true motivation. Will struggles to figure out who's behind his set-up.
Episode: 3x01 | Airdate: Sep 28, 2003
After waking up in Hong Kong, Sydney tries to remember what has happened in the past two years, and discovers that Vaughn is married.
Episode: 3x02 | Airdate: Oct 5, 2003
Jack confronts Sloane, doubting his redemption and blaming him for Sydney's disappearence.
Episode: 3x03 | Airdate: Oct 12, 2003
A fireball drops from the sky, devastating Moscow's Gorky Park.
Episode: 3x04 | Airdate: Oct 19, 2003
A team steals four vials of Ebola from a French epidemiology lab. Lauren and Sydney question Laszlo Bogdan, a team member who was infected and captured.
Episode: 3x05 | Airdate: Oct 26, 2003
Sydney tells Jack to activate the transmitter that she put on Vaughn. Sydney breaks into Simon Walker's room only to find bio-weapon gone and sold to Sark.
Episode: 3x06 | Airdate: Nov 2, 2003
Sloane tells Sydney that intel about the Covenant's next move is encoded in an image of the Vatican on a website.
Episode: 3x07 | Airdate: Nov 9, 2003
Sydney wakes from a nightmare in which she sees an angel-like figure, then pulls tubes from her mysterious scar. Shaken, she asks a CIA psychiatrist about the memory-retrieval process.
Episode: 3x08 | Airdate: Nov 23, 2003
Now in Lindsey's custody, Sydney is imprisoned and tortured at Camp Williams, a secret NSC detention facility.
Episode: 3x09 | Airdate: Nov 30, 2003
Hiding out in a warehouse, the team devises a plan to frame The Covenant for Sydney's extraction.
Episode: 3x10 | Airdate: Dec 7, 2003
Sydney tells Jack about a dream involving Will. Jack advises her to contact Will, who is in the witness protection program.
Episode: 3x11 | Airdate: Jan 11, 2004
Kendall tells Sydney the truth about her two missing years.
Episode: 3x12 | Airdate: Jan 18, 2004
In a North Korean jail, Sydney passionately kisses Vaughn before they are led, in chains, to a firing line.
Episode: 3x13 | Airdate: Feb 15, 2004
At the CIA, the team discusses info gleaned from Lisenker, a Covenant defector.
Episode: 3x14 | Airdate: Mar 7, 2004
Dixon presents the team with a new mission: The Shining Sword, a Filipino terrorist organization, has acquired a next-generation bomb called a plasma charge, which they're shipping to Europe.
Episode: 3x15 | Airdate: Mar 14, 2004
Daniel Ryan, a freelance bomb maker whose bombs are impossible to diffuse, destroys a bank in Belfast as a calling card to The Covenant.
Episode: 3x16 | Airdate: Mar 21, 2004
Senator Reed, Lauren's father, arrives to oversee Sark's interrogation. He tells Jack that they must learn the identity of Sark's partner in The Covenant.
Episode: 3x17 | Airdate: Mar 28, 2004
Vaughn and Sydney travel to mexico city searching for the key to open the Rambaldi box.
Episode: 3x18 | Airdate: Apr 11, 2004
Dixon explains to the team that a computer worm, originating in Berlin, has targeted hospitals, laboratories and universities. They believe it's a Covenant attack.
Episode: 3x19 | Airdate: Apr 18, 2004
Sark takes a manuscript regarding The Passenger, called The Restoration.
Episode: 3x20 | Airdate: Apr 25, 2004
Sloane reveals that he found a Rambaldi text that contained a formula for an elixir that would allow The Passenger to channel a message from Rambaldi.
Episode: 3x21 | Airdate: May 2, 2004
Sloane takes the notes that an entranced Nadia has written and pins them to a board, where they form some kind of diagram.
Episode: 3x22 | Airdate: May 23, 2004
When the mission to kill Vaughn's wife ends up putting Vaughn in the hospital, Sydney decides it's time to kill Lauren. Nadia is forced to decide whether she can trust her father.
Episode: 4x01 | Airdate: Jan 5, 2005
Sydney quits the CIA and joins a Black Ops unit, "Authorized Personnel Only," along with Jack, Vaughn, Dixon, Marshall, Nadia and Sloane.
Episode: 4x02 | Airdate: Jan 5, 2005
What Sydney found out in Wittenburg may endanger her relationship with Jack.
Episode: 4x03 | Airdate: Jan 12, 2005
Sloane says Valta, a computer that will revolutionize info gathering, was stolen from the NSA headquarters by Martin Bishop, who will deliver it to a german terrorist group.
Episode: 4x04 | Airdate: Jan 19, 2005
Sydney and Vaughn are sent on a mission by APO to obtain a sample of Ice 5, a weapon that can freeze a person to death.
Episode: 4x05 | Airdate: Jan 26, 2005
Posing as a Chechen couple, Sydney and Vaughn infiltrate a training camp run by the October Contingent.
Episode: 4x06 | Airdate: Feb 9, 2005
After being infected by a hallucinogen, Sydney starts to lose touch with reality.
Episode: 4x07 | Airdate: Feb 16, 2005
Nadia and Sydney go undercover as wealthy, irresponsible young heiresses to uncover the whereabouts of a deadly chemical.
Episode: 4x08 | Airdate: Feb 23, 2005
Sloane steps down as director of his task force and gives Jack full authority over the next assignment, which involves Anna Espinosa, Sydney's old foe.
Episode: 4x09 | Airdate: Mar 2, 2005
While Nadia is in a coma, Sark is taken into APO to help them infiltrate Cadmus Revolutionary Front and retrieve the bomb.
Episode: 4x10 | Airdate: Mar 9, 2005
Dixon enlists Sydney's to help him prove Sloane is double-crossing the CIA and using APO to steal the Blackwell Index, a master blackmail list.
Episode: 4x11 | Airdate: Mar 16, 2005
Sydney must protect the life of a civilian she unintentionally put in danger.
Episode: 4x12 | Airdate: Mar 23, 2005
Nadia puts the ones she loves in danger when she forgets to tell them about her criminal past.
Episode: 4x13 | Airdate: Mar 30, 2005
When a mission does not go well, Sydney is attacked and her life is put in danger. The only one who can save Sydney is Marshall.
Episode: 4x14 | Airdate: Apr 6, 2005
Jack agrees to Sydney's request for clearence on files relating to Vaughn's father.
Episode: 4x15 | Airdate: Apr 13, 2005
Dixon is shot by a masked gunman. The shooter approaches and takes off his mask, revealing Vaughn.
Episode: 4x16 | Airdate: Apr 20, 2005
In Poland, men posing as airport guards abduct Professor Sinclair, a nuclear physicist. She wakes up bound in a dark room and is greeted by a man impersonating Arvin Sloane.
Episode: 4x17 | Airdate: Apr 27, 2005
The APO team watches footage of an explosion at an Indonesian embassy in Copenhagen that killed 15 people, the work of terrorists headed by Milos Kradic.
Episode: 4x18 | Airdate: May 4, 2005
Sydney 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.
Episode: 4x19 | Airdate: May 11, 2005
The Sloane imposter is questioned about the Rambaldi orchid, but first the real Sloane must remember a painful memory.
Episode: 4x20 | Airdate: May 18, 2005
A tactical group infiltrates the DSR and steals the Rambaldi artifacts. Sophia says goodbye to Nadia and Sydney, telling them that the Lisbon police confirmed that it is safe.
Episode: 4x21 | Airdate: May 18, 2005
A giant version of the Circumference/Mueller device is found floating over a city in Russia, making the citizens insane. Sydney, Nadia and Jack search for Irina.
Episode: 4x22 | Airdate: May 25, 2005
Jack, Sydney, Vaughn and Irina parachute into Sovogda, trying to dismantle a giant red ball turning people into zombies.
Episode: 5x01 | Airdate: Sep 29, 2005
After learning that the man she has known as Michael Vaughn is under investigation and suspected of being a double agent, Sydney begins to question whether their business and personal relationship over the years had all been a lie.
Episode: 5x02 | Airdate: Oct 6, 2005
Sydney visits Sloane in his jail cell. Jack meets with Thomas Grace, a new agent he is recruiting into APO.
Episode: 5x03 | Airdate: Oct 13, 2005
The team interrogates Rachel, a hacker working for Dean, as Sydney realizes they have a lot of similarities.
Episode: 5x04 | Airdate: Oct 20, 2005
A shipping crane lifts Sydney's car hundreds of feet off the ground. Sydney answers her phone - it's Gordon Dean saying he wants Mockingbird.
Episode: 5x05 | Airdate: Oct 27, 2005
Sloane asks to be reinstated in APO so he can find a cure for Nadia. Syd and Tom meet Renee in Marseilles and return to her loft, where the now revived but disoriented man from the box suprises them.
Episode: 5x06 | Airdate: Nov 10, 2005
Sydney must guide a nervous and pensive Rachel on her first solo mission. Sloane must decide whether or not to betray the trust he's recently earned with APO.
Episode: 5x07 | Airdate: Nov 17, 2005
Sloane confesses to Jack and Sydney that he had been working with Dean, as they come up with a plan to trap him.
Episode: 5x08 | Airdate: Dec 7, 2005
Unaware of who the other really is, Rachel and Sark fall for each other while both undercover.
Episode: 5x09 | Airdate: Dec 14, 2005
Hoping to gain information from her, Prophet Five capture Sydney and makes her relive moments of her past with Vaughn.
Episode: 5x10 | Airdate: Apr 19, 2006
Marshall recovers an emergency transmission from Sydney but it's deleted by a Langley insider before he could listen to it - meaning Prophet Five has infiltrated the CIA.
Episode: 5x11 | Airdate: Apr 19, 2006
Irina returns and claiming to want to help, convinces Jack and Sydney to take her on a mission to retrieve The Horizon.
Episode: 5x12 | Airdate: Apr 26, 2006
As part of a plan to bring Sydney back into the field for Prophet Five's own purposes, Peyton has Anna Espinova kidnap Will Tippin.
Episode: 5x13 | Airdate: May 3, 2006
Sloane is distressed to learn that Prophet Five's cure for Nadia is just as likely to kill her. Meanwhile, the search for Anna Espinosa continues, Rambaldi's prophetic Page 47 resurfaces, and Sydney offers Renee a job at APO.
Episode: 5x14 | Airdate: May 10, 2006
Sydney must beat arch-nemesis Anna Espinosa to the punch when a mysterious chip found planted in Renee is tied to Vaughn. Meanwhile, Sloane struggles with ghostly visions while working for Prophet Five.
Episode: 5x15 | Airdate: May 17, 2006
Sydney must stay undercover and partner with Sark to track down Rambaldi's final clue before Prophet Five finds it. Meanwhile, Vaughn sees daughter Isabelle for the first time, and Rachel discovers Tom's secret.
Episode: 5x16 | Airdate: May 22, 2006
Sloane takes Marshall and Rachel hostage in order to discover a crucial clue to Rambaldi's ultimate endgame, as Sydney, Vaughn and APO race to stop him.
Episode: 5x17 | Airdate: May 22, 2006
Sydney and Jack must find a way to keep Sloane and Irina from putting their deadly plan into action.