 Sydney discovers a link to her missing two years in the form of Simon Walker, the dangerous leader of a group determined on retrieving deadly biological weapons. Meanwhile, Vaughn struggles with his own feelings of jealousy and longing while Sydney is on her mission, aware of the pressures his job is putting on his marriage to Lauren. Jack takes matters into his own hands to protect his daughter, and purposefully revealing Sydney s deadly secret of being a brainwashed assassin for the Covenant during her two-year absence to Dixon in order to preserve her position inside the CIA.