A rapist in a fishermans hat and childs Halloween mask is stalking the pretty young girls of Hong Kong. In a scene lifted from John Schlesingers 1990 American Film of the same name, a mother (Angie Cheung) hears her daughter being victimized over her cell phone. This traumatic experience causes Cheungs daughter to take her own life. Shaken and stirred by her loss, mama vows vengeance. She begins some Travis Bickle-esque training and transforms herself into a super sexy, lean, mean, pervert killing machine.

深夜，若珊上网与母亲嘉文交谈，听见厅中有异声往外察看，却被色狼强拉至出客厅侵犯。若珊挣扎逃回房内向嘉文求救，嘉文目睹色狼背部有蝎子纹身但欲救无门，眼白白通过电脑视像看着若珊被奸。事后在警署若珊一口指证乔子扬是非礼犯，但精液化验结果与子扬不吻合，加上他并没有任何纹身，子扬当然否认一切。警署门外若珊遇上子扬发生纠缠，嘉文苦劝中令若珊感到嘉文是否不信自己，羞怒下跳楼自杀，嘉文见女儿倒在血泊中，后悔没有相信若珊，决定用方法使子扬露出狼相。　　一天夜里，色狼真的来了，却被子扬打退，嘉文此时以为误会了子扬，遂邀子扬吃饭道谢，本沉醉于浪漫气氛的嘉文突然发现子扬的鞋子沾有若珊的萤光指甲油，遂质问子扬，子扬露出本来面目，欲非礼嘉文，后嘉文取刀刺伤子扬，嘉文感若珊已沉冤得雪。可是，嘉文收到警察电话，事情却是出乎意外……