Face/Off (1997)

An FBI covert terrorism expert, through advanced plastic surgery, assumes the identity of his arch-nemesis, a sadistic terrorist. Things get complicated when the terrorist awakens from surgery, faceless, and forces the doctors to attach the FBI agent's face. Both characters then carry out one another's lives in a game of cat-and-mouse--the FBI agent pretends to be the terrorist while trying to locate and dismantle a nuclear weapon, while the terrorist assumes the role of FBI agent and family man.