Wong Kam-Kwei, a gang boss on the decline, overseeing bathhouses and karaoke bars, falls for a small restaurant owner, Mei. He begins to help her business, and learns that Mei is already in love with Leung, a member of his gang. He’s also like a brother to Kam-Kwei. When a rival gang hoping to steal his territory kills Leung, the only thing left for Kam-Kwei to do now is to protect Mei and avenge Leung.

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.