Alan Mak

Months after the events of the original film, Ming suspects a police superintendent as being a new mole for the triads, while years earlier, Yan embarks on his first mission.

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.

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.