Sydney Bristow is a grad student by day, international spy by night. Her happiness over new new engagement is short-lived as she learns some truths about who she works for.
Sydney and Vaughn must destroy a familiar-looking device in order to save Will's life while Jack makes a risky deal with Mr Sark, and the Alliance comes to a decision about Emily Sloane.
Jack meets Alliance counterintelligence head Ariana Kane, who is probing Emily's disappearance. Sydney partners with Marshall on his first mission.
Marshall's life is placed in mortal danger after he finishes his first mission with Sydney. Ariana Kane targets Jack as the prime suspect in the disappearance of Sloane's wife.
Season three of the action drama series. Nadia writes cryptic words in an unknown language. Vaughn attempts to reconcile himself to Sydney. Vaughn and Sydney infiltrate the bunker where the elixir is, only to discover that they have been beaten to it.