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.

Sydney teams up with Renée - a fugitive on the CIA's most wanted list -- to track down the murderer of a close friend before the killer can strike again. Meanwhile, Jack enlists a reluctant new agent, Thomas Grace (Balthazar Getty), and Weiss struggles to decide whether or not to accept a promotion that would force him to leave his colleagues.