Cop Tat Fung (Jackie Chan) is forced to give up his dream of sailing around the world to look after his mentally retarded brother, Do-do (Sammo Hung). When Do-do becomes involved in a gangland battle for some stolen jewels, he is kidnapped and held to ransom. His captors force Tat into a corner when they instruct him to hand over a police informant in return for his brother's life.