After Sergeant Lau has been murdered, his partner Pitt vows to get the killer. By a series of investigations, Pitt finds a witness Fatty, who's persuaded to testify against the killer, Tiger. But Tiger is bailed by Kim, a lawyer. Then Tiger firebombs Fatty's house, making Fatty move into Pitt's home and gain a friendship with Angel, Pitt's sister who is a reporter. Tiger strikes back again and catches Pitt and Fatty. May, who's beguiled to Hong Kong and forced to be a prostitute by Kim, comes to rescue the two men. With the help of May, they manage to get another set of obscene photos, from which they know Superintendent Kueng is involved. Meanwhile, Tiger attacks May and arrests Angel from Pitt's home, forcing Pitt to hand over the photos. Finally Pitt and Fatty manage to put Tiger and the lawyer, as well as Kueng behind bars. (Joy Sales)