FBI agent Sean Archer (John Travolta) must go undercover to investigate the location of a lethal biological weapon planted by his arch rival, terrorist-for-hire Castor Troy (Nicolas Cage). After undergoing a radical surgical procedure, Archer literally "borrows" Troy's face and identity to carry out his mission. But things go awry when Troy, emerging from a coma, is transformed into Archer and wreaks havoc upon his life, both at work and at home.