A determined homicide detective assigned to take down a ring of serial killers, has a personal motivation as one of the victims is his own brother-in-law.

Having lost his colleague who was also his brother-in-law to a serial murderer two years ago, homicide detective Jae-hwan is unable to contain his hatred toward the murderer and dives headfirst into hunting the brutal killer. Jae-hwan finally comes face to face with the murderer Jin-hyeok but in the heat of the chase, they get into an accident. Waking up in a hospital, Jae-hwan realizes his body has been switched with that of the murderer. To protect his family and uncover the secret of this body switch, Jae-hwan, who's trapped in the murderer's body, begins a desperate chase.—hancinema