After making a shocking discovery of a severed human hand in the desert that belonged to Lazarey, the Russian diplomat she murdered while working as a brainwashed assassin for the Covenant, and who may in fact be alive, Sydney agrees to submit to an experimental procedure conducted by an eccentric doctor, named Dr. Brezzel, designed to retrieve her lost memories. But while Jack and Vaughn look on, Sydney's mind proves surprisingly resistant to letting her remember her missing time... and the process of recovering it could end up killing her. Meanwhile, Lauren makes a great sacrifice of allowing herself to get tortured and beaten up in order to make her alibi believable to Lindsey after helping breaking Sydney out of NSC custody. Also Sloane finds himself boxed in by an unlikely enemy, that of Mr. Lindsey, who wants to see Sydney Bristow eliminated permanently.

The identity of the mysterious "St. Aidan" forces Sydney to pull a stunned Will Tippin out of witness protection for help in finding Lazarey to clear her name. But the pursuit sends the two old friends on a collision course with Allison, the Francie impostor who ruined both their lives. Meanwhile, a jealous Lindsey arrests Jack and Vaughn as conspirators in Sydney's escape from NSC custody. Sloane, still under pressure from Lindsey, puts a plan in motion to eliminate Sydney, and Dr. Brezzel has an unpleasant run-in with Sark whom is also looking for Sydney.