> episode 4.01 -- "Authorized Personnel Only, Part 1"     airdate: 01-05-05

(back-to-back premiere with episode 4.02)

Sydney, Vaughn, Jack and Dixon are stunned by CIA Director Hayden Chase's (Angela Bassett) choice to be their new boss. Meanwhile, Sydney and Vaughn's possible reconciliation is surprisingly in doubt -- even though Lauren is dead -- and Sydney learns an appalling secret about Jack that threatens to destroy their relationship. Additionally, against Sydney's vehement objections, her new boss partners her with Jack to hunt down a modern-day samurai; Sydney's half-sister, Nadia, is reluctant to return to the spy game since learning the truth about her father -- Arvin Sloane; and Vaughn and Jack share a surprising bond over Jack's unspeakable past misdeed - much to Sydney's chagrin.

> episode 4.02 -- "Authorized Personnel Only, Part 2"     airdate: 01-05-05

(back-to-back premiere with episode 4.01)

Sydney, Vaughn, Jack and Dixon are stunned by CIA Director Hayden Chase's (Angela Bassett) choice to be their new boss. Meanwhile, Sydney and Vaughn's possible reconciliation is surprisingly in doubt -- even though Lauren is dead -- and Sydney learns an appalling secret about Jack that threatens to destroy their relationship. Additionally, against Sydney's vehement objections, her new boss partners her with Jack to hunt down a modern-day samurai; Sydney's half-sister, Nadia, is reluctant to return to the spy game since learning the truth about her father -- Arvin Sloane; and Vaughn and Jack share a surprising bond over Jack's unspeakable past misdeed - much to Sydney's chagrin.

> episode 4.03 -- "The Awful Truth "     airdate: 01-12-05

To learn the location of a stolen NSA code-breaker, an undercover Sydney must convince a murderous arms dealer to fall in love with her. Meanwhile, Vaughn fears that Weiss might have been killed on a mission, and Sydney and Jack argue about telling Nadia the horrible truth about her mother, Irina.

> episode 4.04 -- "Ice"     airdate: 01-19-05

Sydney goes undercover as an earthy social worker and Vaughn as a lascivious, semi-tipsy priest to track down a deadly new bio-weapon. Meanwhile, Sydney is frightened when Vaughn's inner-demons regarding deceased wife Lauren come to the surface, and Nadia turns to a reluctant Jack to learn truths about her mother.

> episode 4.05 -- "Welcome To Liberty Village"     airdate: 01-26-05

Sydney and Vaughn pose as a married couple in suburbia in order to find a weapon that could set society back to the Dark Ages. They quickly discover that "marriage" is a real strain on their relationship, and the picturesque neighborhood they've infiltrated is not nearly as innocuous as it seems - nor is it in America.

> episode 4.06: "Nocturne"     airdate: 02-09-2005

Sydney becomes infected with a mind-altering and potentially deadly hallucinogen, causing her to slowly lose touch with reality. Vaughn and Jack must scramble to find an antidote before Sydney's hallucinations, paranoia and resultant violent behavior threaten her life and the lives of those around her.

> episode 4.07: "Detente"     airdate: 02-16-2005

While Sydney and Nadia argue about Nadia's acceptance of Sloane's fatherly concerns, Sloane worries about Nadia's well-being when she and Sydney go undercover as wealthy, irresponsible young heiresses to uncover the whereabouts of a deadly chemical.

> episode 4.08: "Echoes"     airdate: 02-23-2005

With Nadia’s life on the line, Sydney must race to bring down former nemesis Anna Espinosa (Gina Torres, “24”). Meanwhile, Vaughn’s inner demons surface when, in order to help Sydney save Nadia, he’s forced to confront his own former nemesis, the slippery and deadly Mr. Sark (David Anders).

> episode 4.09: "A Man of His Word"     airdate: 03-02-2005

Sark agrees to help Sydney and Vaughn track down Anna Espinosa (Gina Torres, “24”), but only after Vaughn agrees to a despicable request from Sark (David Anders) related to Lauren’s buried corpse. Meanwhile, Jack ponders risking Nadia’s life by prematurely reviving her from an induced coma to extract vital information about Anna’s whereabouts.

> episode 4.10: "The Index"     airdate: 03-09-2005

**from ABC -- Sydney's theory that Sloane is trying to re-form the Alliance threatens her relationship with Nadia, who refuses to believe her father is double-crossing the CIA. Meanwhile, Vaughn learns the first of possibly many startling secrets about his father.

> episode 4.11: "The Road Home"     airdate: 03-16-2005

While on a mission in Germany, Sydney inadvertently places the life of an American civilian in jeopardy and must do all she can to get him out of harm's way. Meanwhile, Jack plans a deadly visit with an old friend, and Vaughn uncovers even more unsettling secrets about his father.

> episode 4.12: "The Orphan"     airdate: 03-23-2005

After failing to disclose her tainted past with a man who is now the focal point of the agency's mission, Nadia places her life as well as the lives of Sydney and Weiss in grave danger. Meanwhile, Vaughn discovers someone with ties to both his father and Nadia.

> episode 4.13: "Tuesday"     airdate: 03-30-2005

Sydney's life hangs in the balance when a mission goes awry -- and Marshall, surprisingly, is the only one who might be able to save her. Meanwhile, Dixon is exposed when a deadly pathogen is released inside APO.

> episode 4.14: "Nightingale"     airdate: 04-06-2005

Sydney and Vaughn risk their lives and careers searching for the truth about Vaughn's presumably deceased father. Meanwhile, it's unclear why Jack and Sloane seem to be conspiring with each other and against Sydney and Vaughn, and Jack faces a potentially deadly choice that will forever change his life and Sydney's.

> episode 4.15: "Pandora"     airdate: 04-13-2005

Sydney learns devastating news from her aunt, Katya Derevko (Isabella Rossellini), about her mother, Irina's death. Meanwhile, Vaughn becomes a rogue agent when he steals a device to use as a bargaining tool in order to learn the truth about his father, and Marshall questions Jack's health. 

> episode 4.16: "Another Mister Sloane"     airdate: 04-20-2005

Sydney must ally herself with Sloane in order to catch the man (Joel Grey, Broadway's "Wicked," "Cabaret") who has been impersonating him. But when they discover what the imposter is after, Nadia begins to worry that her father will be tempted to rediscover a past obsession.

> episode 4.17: "A Clean Conscience"     airdate: 04-27-2005

Sydney and Nadia are shocked to discover that Sophia (Sonia Braga, "American Family," "Kiss of the Spider Woman") -- the head of the orphanage that cared for Nadia as a child -- has been severely beaten. But Sloane fears for Nadia's life when he learns the reason for the beating. Meanwhile, Dixon is faced with a life-altering moral dilemma while on a mission with Vaughn, and Jack's doctor (Michael McKean, "Best in Show," "This is Spinal Tap," "Laverne & Shirley") offers some advice to his ailing patient.

> episode 4.18: "Mirage"     airdate: 05-04-2005

Sydney is shocked when she discovers that Jack is terminally ill -- and that he chose not to tell her. Meanwhile, Nadia's orphanage caregiver, Sophia (Sonia Braga, "American Family," "Kiss of the Spider Woman"), continues her convalescence at Sydney's apartment. Michael McKean ("Best in Show," "This is Spinal Tap," "Laverne & Shirley") guest stars as Jack's doctor.

> episode 4.19: "In Dreams..."     airdate: 05-11-2005

This episode marks Jennifer Garner's directorial debut -- The mysterious man (Joel Grey, Broadway's "Wicked," "Cabaret") who has been impersonating Sloane resurfaces, and this time he's hot on the trail of Rambaldi. Meanwhile, shocking revelations about the real Sloane are brought to light, causing everyone to further question his true intentions. Amy Irving ("Traffic," "Yentl") guest stars as Emily Sloane.

> episode 4.20: "The Descent"     airdate: 05-18-2005

This episode, along with 4.21:"Search and Rescue,"  aired as a two-hour program.

After learning the awful truth about Nadia's childhood caregiver, Sophia (Sonia Braga, "American Family," "Kiss of the Spider Woman"), APO races to track her down while an agent's life hangs in the balance. Meanwhile Sydney and Nadia question Sloane's trustworthiness now that his obsession with Rambaldi may have been renewed, Jack has an unsettling meeting with Katya Derevko (Isabella Rossellini), and Vaughn asks Jack a surprising and momentous question. Angela Bassett guest stars as Hayden Chase.

> episode 4.21: "Search and Rescue"     airdate: 05-18-2005

This episode, along with 4.20:"The Descent" which precedes it, aired as a two-hour program.

Upon discovering that Irina Derevko (Lena Olin) is alive, Sydney, Jack and Nadia set out to find her in order to thwart Elena Derevko's (Sonia Braga, "American Family," "Kiss of the Spider Woman") deadly Rambaldi endgame. Meanwhile, Dixon's condition takes a turn for the worse. Angela Bassett guest stars as Hayden Chase.

> episode 4.22: "Before the Flood"    [season finale]     airdate: 05-25-2005

Sydney, Jack, Irina (Lena Olin), Vaughn and Nadia are the last hope to save the world from the catastrophic effects of the Rambaldi end game -- put into action by Elena Derevko (Sonia Braga, "American Family," "Kiss of the Spider Woman"). Meanwhile, the Rambaldi prophecy surrounding Sydney and Nadia comes one step closer to becoming reality, Sloane's true allegiances are realized, and Vaughn asks Sydney a momentous question.