Sydney Bristow is a grad student by day, international spy by night. Her happiness over new engagment is shortlived as she learns some horrible truths about who she works for.

Jack's illness has caused him to hallucinate about a cure. Sydney must recreate the time when Jack was working for the CIA and hid the only man who might be able to help him now. For this, Sydney must play her own mother. Meanwhile, Sophia moves in with Sydney and Nadia.

The mysterious man (Joel Grey) who has been impersonating Sloane resurfaces, and he is hot on the trail of Rambaldi; shocking revelations about the real Sloane come to light, making everyone question his true intentions.

An agent's life hangs in the balance as the team races to track down Nadia's childhood caregiver, Sophia (Sonia Braga); Sydney and Nadia question Sloane's trustworthiness now that his obsession with Rambaldi has been renewed.

Jack, Sydney and Nadia learn that Irina Derevko (Lena Olin) is alive, and they head out to find her to thwart Elena Derevko's (Sonia Braga) Rambaldi scheme.

Only Sydney, Jack, Irina, Vaughn and Nadia can save the world from the plan put into motion by Elena Derevko (Sonia Braga); the Rambaldi prophecy regarding Sydney and Nadia comes one step closer to being reality.

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. When she discovers that she’s pregnant with Vaughn’s baby, she becomes determined to uncover the truth about him. Meanwhile, because of Jack's past betrayal by Irina, he begins to worry that his daughter may suffer the same fate that he did.

Sydney must team up with a fugitive on the CIA's most-wanted list in order to track down the murderer of a close friend before the killer can strike again.

Fresh from Vaughn's death, Sydney is forced to partner on a mission with new APO agent Thomas Grace. They discover that Rachel Gibson -- a spy suspected of being involved in activities against the U.S. -- has something shockingly in common with Sydney. Meanwhile, Dixon must accompany Sloane, who's given a 48-hour pass from prison to acquire a possible cure for his daughter, Nadia.

While Sloane awaits the outcome of his sentencing, Sydney's life is put in grave danger when Gordon Dean discovers that Rachel is still alive.

Sydney and Tom discover that Renée has stolen the cryogenic-type container, and they find themselves under siege by mercenaries who want the container's contents. Meanwhile, Sloane is forced to take matters into his own possibly devious hands to get himself reinstated into APO and to continue his quest to find a cure for daughter Nadia.

Sydney must guide a nervous and pensive Rachel on her first solo mission; Sloane contemplates honoring his agreement with Gordon Dean.