Yat Si takes over a series of rape and murder cases and arrests a suspect on the spot. Yet the crimes continue and the killer is caught on camera. However Yat Si cannot confirm the identity of the killer. He discovers that his girlfriend Hiu Man is the next target. A series of murder occurs and because they take place in a closed room, he believes a professional is involved. Before Yat Si begins, he starts to suspect the killer might be Chinese legend's Bull Head Horse Face (guardians of Hell) and feels his own life is endangered...
