 FBI Special Agent Sean Archer tries to find a biological weapon placed in Los Angeles by a sadistic terrorist-for-hire and criminal mastermind named Castor Troy. Archer has hunted Troy for the last 8 years, and is consumed by revenge because Troy is responsible for the death of Archer s son. To do this, Archer must "borrow" Troy s face using a surgical procedure to go undercover as Troy, but things go wrong when Troy assumes the identity of Archer.