I Saw the Devil

Synopsis:

Kyung Chul is a sadistic serial killer who preys on women and children. Despite the police’s efforts, he remains elusive. When his latest victim, Joo Yeon, the daughter of a retired police chief, is found brutally murdered, her fiancé, Soo Hyun, a top-secret agent, vows to hunt down the killer. He is determined to exact bloody vengeance, even if it means becoming a monster himself.