As rumors circulate that the long-disappeared Indian gang boss known as Black Molly is about to return to the underworld, Tactical Unit officers Sam (Simon Yam) and May (Maggie Shiu) are prepared to tackle the ensuing troubles. Molly's right-hand man Velu decides to quit the gang after serving a prison term, but his former partner Sonu feels betrayed, and vows to kill him. Meanwhile, Sonu is driven down the path of no return when he gets assigned the job of assassinating Chief Inspector Chan, Sam and May's superior.