2-hour season premiere

In the season premiere episode, 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 Sloan; and Vaughn and Jack share a surprising bond over Jack's unspeakable past misdeed - much to Sydney's chagrin. Written by J.J. Abrams & Jeff Melvoin, directed by Ken Olin.

Rating: 9.7/15

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. Written by Jesse Alexander, directed by Lawrence Trilling.

Rating: 8.9/13

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. Written and directed by Jeffrey Bell.

Rating: 8.2/12

Syd and Vaughn go Stepford to infiltrate a Russian terrorist program that trains operatives to pose as suburban American couples. Back at APO, Jack and Sloane are forced to rethink their secret pact after Irina's former mentor comes forward looking for another Derevko. Written by Drew Goddard, directed by Kevin Hooks.

Rating: 7.3/11

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. Dixon lets Sloane in on plans for bringing him down.

Rating: 6.7/10

Syd and Nadia teach the APO men a thing or two about teamwork when they suit up to steal info from a Russian oil magnate about his very explosive new venture. But while the sisters set off sparks, tensions between Sloane and one of his agents reach a boiling point that could leave a certain spy out in the cold. Written by Monica Breen & Alison Schapker, directed by Craig Zisk.

Rating: 6.4/10

The Rambaldi prophecy casts its dark shadow over Syd after her sworn enemy Anna Espinosa (Gina Torres) returns with a deadly plan for Nadia, forcing Vaughn to strike a deal with Sark for intel on the lady killer's new boss. Sark: David Anders. Written by André Nemec & Josh Appelbaum, directed by Daniel Attias.

Rating: 6.0/9

With Nadia in a coma and Anna Espinosa (Gina Torres) on the run, Sloane is forced to negotiate with Sark (David Anders) for info on what Anna plans to do with the bomb she's swiped. But when Vaughn and Syd learn the details of the Sloane-Sark deal, they realize that a ghost from their past needs to rise if they hope to bring down Espinosa. Written by Breen Frazier, directed by Marita Grabiak.

Rating: 6.3/9

A vengeful Dixon pushes his luck with Chase (Angela Bassett) to prove that Sloane is working with his old Alliance cronies to decode a top-secret database. But when Syd gets in on the investigation, she realizes that busting Sloane means betraying Nadia. Meanwhile, an ailing relative leads Vaughn to a surprising discovery about his late father.

Rating: 6.3/9

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.

Rating: 5.6/8

Nadia's past plays out in flashback as a mission to retrieve a stolen laser-beam magnifier reunites her with a man she should have forgotten about years ago. Meanwhile, Vaughn has guy problems of his own when a trip to his father's last-known whereabouts takes an unexpected turn.

Rating: 4.5/7

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.

Rating: 6.7/10

Double crosses blur the lines between good and evil after Jack and Sloane use Vaughn's search for his father to find a no-so-dead Derevko. But when a rogue mission goes awry, one of them must risk his life to save Sydney from a nuclear trap that could spell the end of one APO member. Dietrich: Robin Sachs. Vlachko: Elya Baskin.

Rating: 6.2/9

A rogue Vaughn is lured into helping a shady strike force steal a very familiar manuscript in exchange for the truth about his father...and the person behind his demise. Back at APO, Nadia's covert charts with aunt Katya (Isabella Rossellini) put Syd on the paper trail of the man she thought irina had hired to kill her; Marshall confronts Jack with the grim consequences of his semi-heroics; and an ambush leaves Dixon at the mercy of one of his colleagues.

Rating: 5.0/8

The APO team takes on a new field member---Sloane---after it becomes clear that his imposter (Joel Grey) is after the same Rambaldi designs that led to the rise and fall of SD-6's mastermind. But old obsessions threaten to resurface and ruin Nadia's hopes of saving her father's soul. Roberts: Michael Kenneth Williams.

Rating: 5.6/9

Sydney and Nadia are shocked to discover that Sophia (Sonia Braga) -- 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) offers some advice to his ailing patient.

Rating: 5.4/8

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), continues her convalescence at Sydney's apartment. Michael McKean guest stars as Jack's doctor.

Rating: 5.7/9

The mysterious man (Joel Grey) 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 guest stars as Emily Sloane. Directed by Jennifer Garner.

Rating: 6.5/10

After learning the awful truth about Nadia's childhood caregiver, Sophia (Sonia Braga), 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.

Rating: 5.5/9

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) deadly Rambaldi endgame. Meanwhile, Dixon's condition takes a turn for the worse.

Rating: 5.5/9

Season finale

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). 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, on the season finale.

Rating: 6.5/10