Big Guy (played by Andy Lau) encounters police officer Li Fengyi (played by Cecilia Cheung) while performing a striptease, as anti-vice police are performing a raid. Meanwhile, a homicide investigation regarding an Indian man is underway nearby. During his escape, Big Guy unexpectedly meets the fleeing Indian fugitive, who ultimately manages to escape, while Big Guy is mistakenly captured as a suspect and taken back to the police station. In fact, Big Guy was once a martial monk in mainland China, and after his friend Xiaocui died tragically, he was overwhelmed with grief. Under a tree, he accidentally killed a bird, and sat in meditation for seven days and nights in front of it, during which he gained the ability to see cause and effect — when he sees an outcome, he can see its causes. He realized that Xiaocui's death was a result of karma and that he killed the bird was also a consequence, and unable to peacefully accept all of this, he returned to layman's life. This time, he saw Li Fengyi and witnessed the Japanese army committing murder, which made him aware that her sins were too heavy, and she would encounter disaster. To help this kind-hearted police officer, he began to secretly assist her, helping her solve difficult cases and rescue her from danger, hoping to help her atone for her sins...
