Little cop (1989)

Ever since he was a child, Lee Chi-kin has been determined to become a police officer, despite the fact that he comes from a family of criminals. As an adult, he joins the police force, where he is first placed with the Narcotics Bureau. During a drug raid operation, he catches a drug dealer. He is later transferred, first to the Anti-Porno Bureau where he falls in love with a call girl, then to the Regional Crime Unit where he works under Inspector Chu. During a drug raid operation, Lee kills drug lord Ng Cheung. Ng's father hires a killer, Thousand Faces Man to take revenge on Lee. After several confrontations, Lee finally brings Thousand Faces Man to justice. The corrupt director of a mental hospital places Lee in the mental hospital for a year, during which time he develops mental disorders. After being discharged from the hospital, he becomes a restaurant waiter.