An undercover cop badly injured in a raid is blamed for the raid's failure and thrown out of the police department. His injuries result in his being paralyzed form the waist down, and doctors tell him that if he doesn't have an operation within a few months, the paralysis will be permanent. His friends in the police department decide that, since the underworld was responsible for their friend's injuries, the money for the operation should come from them, and they set out to get it.

Lin is a plain-clothes cop in the crime-riddled district of Mongkok who bungles a vice operation directed at mainland prostitues. He falls for a ditsy hooker who tells him the love of her life is a killer who once svaed her life in a shootout.