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.

The chief investigator of ICAC Chan King-chi (Sean Lau)'s childhood friend Hui Chik-yiu (Nick Cheung) does a spy job in the smuggler company even after he mysteriously fleets to Australia.

A story between a mole in the police department and an undercover cop. Their objectives are the same: to find out who is the mole, and who is the cop.