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.
In the underbelly of the Parisian criminal world, the Police are frustrated by a gang committing a series of violent robberies. Leo Vrinks and Denis Klein are two cops seeking promotion, and the imminent departure of the Chief sets the scene for them to compete for the vacant throne. The competition between them becomes increasingly ruthless and blurs the usual lines of morality, until there seems no difference between the police and the criminals they chase. Vrinks, meeting with a source, becomes involved with a murder. Klein seizes the opportunity to up the ante and arranges for the arrest of Vrinks, but when he goes further and viciously involves Vrinks' wife, Camille, revenge is inevitable.
A teacher lives a lonely life, all the while struggling over his son's custody. His life slowly gets better as he finds love and receives good news from his son, but his new luck is about to be brutally shattered by an innocent little lie.
A rich industrialist is brutally kidnapped. While he physically and mentally degenerates in imprisonment, the kidnappers, police and the board of the company of which he is director negotiate about the ransom of 50 million euro.