Seven years ago undercover police officer Mike (Michael Wong) made the grave mistake of saying "I love you" to a thief he was tailing (Almen Wong). When a girl named Lily Wong, died in a bungled sting, the seeds of a vengeful ghost were sown. Fast-forward to 1999 Hong Kong and Lily finds her man breaking his mock-promise of undying love. Unimpressed, she assumes the body of an angry young cop to punish Mike and his family. Mike's wife (Ng) is the first target. Intriguingly the Lily says her aim is not to kill the wife, but instead to make her "slowly dead". Not coincidentally, Mike's mother-in-law (Law Lan) has been investigating Mike's supernatural side for two years. All-knowing about his predicament, she ultimately launches him into the past; condemned to repeat Lily's death scene and become dead to his family.