Mongkok, Hong Kong, one of the most densely populated areas in the world, is a hotbed for illicit business. Lai Fu, a farm boy from Mainland China, is hired as a killer and is forced to enter into the gang world of Mongkok. Lai Fu by chance meets a call girl from his home village, Dan, and saves her from the gangsters. Under flashy neon lights, Lai Fu and Dan are chased around in Mongkok by police and triads alike. Who will find them first, the lawful force or the lawless one?