Chan Wing Yan, a young police officer, has been sent undercover as a mole in the local mafia. Lau Kin Ming, a young mafia member, infiltrates the police force. Years later, their older counterparts, Chen Wing Yan and Inspector Lau Kin Ming, respectively, race against time to expose the mole within their midst.
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.
In a city of love and prosperity, a city of lost hope and premature death, veteran detective Hei feels it all: the hurt, the helplessness, the horror. When his father-in-law, the billionaire benefactor Kim, is gruesomely murdered in his palatial mansion, he enlists the assistance of his former partner turned private detective.
