The film stars Chow Yun-fat and Conan Lee as a buddy cop team who originally hate each other, but learn to overcome their differences in solving a case.

This action-comedy film in the style of Lethal Weapon is about a lazy police veteran Francis Li (Chow Yun-fat) and his eager rookie partner Michael Tso (Conan Lee).

The pair of mismatched partners are assigned to investigate the murder of a heroin trafficker "Poison Snake" Ping (Phillip Ko) who was known to be associated with crime boss Johnny Law (Norman Chui).

The duo interrogate bar girl Marydonna (Nina Li Chi) who is the sister of "Poison Snake" Ping, one of Law's associates.

Though the criminal soon winds up in jail and Li gets his long overdue promotion, Law is all out for revenge.