Detective Iron Man (played by Ren Dahua) accidentally kills his own brother while on a mission, leaving him with a psychological scar that causes erectile dysfunction. After encountering the troubled girl Kitten (played by Qiu Shuzhen), he discovers that his condition improves whenever he sees her, and Kitten also likes him. Following an incident where Kitten commits murder and goes missing, she is rescued by professional female assassin Sister Four (played by Yao Wei) and trained to become a killer. Sister Four's top apprentice, Princess (played by Wu Jiali), is a lesbian with a vicious killing style. She is dissatisfied with Sister Four and harbors fantasies about Kitten. A series of homicides reunites Iron Man with Kitten, who denies her identity, but Iron Man is convinced she is Kitten. Both Sister Four and Princess want to eliminate the troublesome detective, but Kitten protects him at all costs. Soon after, for her own benefit, Princess cruelly kills Sister Four. In an act of revenge for her mentor, Kitten lures Princess into a trap, planning for them to perish together. In a moment of crisis, Iron Man arrives and, seeing the gravely injured Kitten, makes a decision he will never regret for the rest of his life.
