Sergeant Tong is wracked with guilt after he unwittingly kills a young girl whilst capuring a criminal named Cheung. When the girl's sister is later kidnapped in a ploy to get Cheung released, Sergeant Tong vows to find and rescue her before she comes to harm.
The story revolves around three members of a police surveillance squad conducting an investigation into a financial investment group involved in criminal fraud. The focus of the plot, however, is actually on the three officers themselves who stumble upon an opportunity to capitalize on information they gathered during their surveillance.
By a strange twist of fate, dutiful Hong Kong policeman Dan saves the life of the leader of a violent gang of armed robbers. When they commit another crime, Dan is determined to put an end to their activities. He works with the leader, whom the gang had betrayed, to engineer a plan to wreak havoc within the gang and let the gangsters kill one another. But it becomes increasingly obvious to Dan and to his colleagues that Dan is suffering from a severe mental disorder, and Dan finds that instead of upholding the law as a righteous police officer, he has now become a fugitive wanted for murder.
