Another unidentifiable body was found, and the local police invited Special Agent Elena Scott (Angelina Jolie Angelina Jolie) to assist in the investigation without making any progress on the investigation. Scott's unjustifiable way of handling cases aroused the dissatisfaction of his colleague Pickett, but with his keen intuition and extraordinary insight, Scott quickly figured it out: the criminal suspect Martin Ash has been acting as other people's lives for 20 years. After each murder, he will play the identity of the deceased to start a new life. Costa (Ethan Hawk Ethan Hawke) is an eyewitness to the last murder, and the two like each other when working with Scott, but as a police officer, Scott always keeps a distance from him. On the day of the end of the serial murder, the deep-buried feelings between the two men finally broke out. The day after the two had sex, Scott saw James kill the suspect's mother in the elevator when she realized she was falling into a trap. The film is based on a novel of the same name by the British novelist Michael Pye.