The Diamond Gang commits a robbery. The leader Chiu Yee-kong wants to keep the booty and this arouses the suspicion of gang member Tai-wai. The police does not have a clue and thus invite Wong Ngung, Heung Ad and Wu Ngar for help. Kong is in accomplice with his third concubine. They order someone to steal the diamond and leave Wong's symbol. Wai turns his attention on Wong. Wong, Ad and Wu are not afraid of Wai and they throw him out. They sneak in Kong's apartment to investigate. Kong's second concubine is mad at Kong for neglecting her. She tells Wong the truth but gets killed. Kong's people surround Wong, Ad and Wu. Each of the three faces their enemy. Ad is tortured by Wai. Wong and Wu arrive in time and save her. One of Kong's people tells Wai the truth. Wai immediately attacks Kong. Wong, Ad, Wu and the police arrive at Kong's headquarter to arrest the gangsters. Wai is arrested but Kong has escaped. The diamonds are found. The inspector makes Wong, Ad and Wu as partners.