Alias - Season 3 - Eps 4: A Missing Link
Sydney discovers a link to her missing two years in the form of Simon Walker, the dangerous and sexy 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, purposefully revealing Sydney's deadly secret to Dixon in order to preserve her position inside the CIA.
About Alias

Title: Alias
First Air Date: 2001-09-30
Last Air Date: 2006-05-22
Status: Ended
Rating: 6.736/10 (from 645 votes)
Language: EN
Seasons: 6
Total Episodes: 105
Network: ABC
Genres: Action & Adventure, Drama
Production Companies: Bad Robot, Touchstone Television
Synopsis
Sydney Bristow, an agent who has been tricked to believe she is working for the U.S. government, is actually working for a criminal organization named the Alliance of Twelve. Upon learning this, Sydney becomes a double agent for the real CIA.
Cast

Jennifer Garner
Sydney Bristow

Michael Vartan
Michael Vaughn

Victor Garber
Jack Bristow

Ron Rifkin
Arvin Sloane

Carl Lumbly
Marcus Dixon

Kevin Weisman
Marshall Flinkman

Rachel Nichols
Rachel Gibson

Amy Acker
Kelly Peyton