Anthony Chau-Sang Wong

In this prequel to Mou gaan dou (2002), Chan Wing Yan has just become an undercover cop in the triads while Lau Kin Ming joins the police force. Both the triads and the police find an enemy in a rival crime boss.

Jonah Mulray is a professor whose world comes crashing down when his wife is killed in a car crash in Hong Kong.

Chen Wing Yan, a policeman, successfully infiltrates a gang while Lau Kin Ming, a triad member, becomes a mole in the police force. However, things change when both of them must seek each other out.