Singapore detective Lung Chieng-tien is holidaying in Japan when his father is murdered back in Singapore. He rushes back home only to find his father's tape-recorded voice telling him a story of crime and punishment: Old Lung and two friends were dealing in narcotics. He decides to quit but Chen threatened him and he had to carry on. When the son became a policeman, the father secretly supplied him with information. Chen was after him. Chang tells Lung that Chen is the murderer and is now in Hong Kong, having changed his name to Wong. Lung goes to Hong Kong......