Tsao Chan (Gordon Liu) is a letter carrier in the countryside who wanders into a town after being accosted by some corrupt cops. He witnesses three men running from a group of houses, and when he investigates he finds two murder victims inside. Meanwhile, a skirmish is developing between a factory owner (Fung Hak On) and his workers, led by two brothers (Paul Chin and Dean Shek). Tsao recognizes the brothers as two of the men fleeing the murder scene, so he decides to ally with the factory boss in order to go solve the crime. Soon though, it becomes clear that the boss and his thugs may have other things in mind that aren't so kosher. Tsao becomes trapped in the middle of the feuding groups and must decide who is honest and who is not.

A serial murderer has brutally killed several policemen and their pregnant wives. After a quick investigation, the murderer is revealed to be Kit, whom the case's detective-in-charge knows from a previous case. Once upon a time, Kit was an innocent boy in a rural village who also has a crush on naïve high school student Wing. After the death of Wing's grandmother, Kit rescues Wing from a foster care facility, and the two quickly fall in love. However, their romance ends prematurely when a local policeman arrests them. The events that follow lay the seeds for Kit's terrifying path to vengeance.