A deadly car accident threatens to cause a violent gang war on the crowded streets on Hong Kong’s Mongkok district in writer/director Derek Yee’s thriller One Night in Mongkok. Officer Milo (Alex Fong)’s task force is assigned to the case when a gangster’s son is accidentally killed during a drunken dispute with a rival gang. He soon learns that a hitman has been hired to take out the rival gang leader. While Milo and his crew desperately try to find and stop the hired gun, fearing all-out war in the streets, Lai Fu (Daniel Wu), a smart but inexperienced killer from a small town in the mainland, arrives in Hong Kong to do his job. A decent sort, he intercedes when he sees a thug threatening a prostitute at his hotel. She turns out to be Dan Dan (Cecilia Cheung from Running on Karma), from a small town not far from his own. Dan Dan is a very practical young woman, and when she sees the wad of cash Lai Fu is carrying (half of his payment for the job), she pretty much latches onto him. Since she knows her way around town, this turns out to be a help to Lai Fu when he finds out that the contractor who hired him has ratted him out to the cops. As it turns out, Lai Fu isn’t really that interested in killing for money, and has an ulterior, more benign motive for his trip into town.