Set during the Ming Dynasty, the story follows four legendary constables—Cold-Blooded, Iron Hands, Life Snatcher, and Emotionless—who serve under the Department of Six Gates. Each member possesses unique martial arts skills and distinct personalities, working together to solve complex crimes and maintain order in the capital while uncovering deep-seated conspiracies within the imperial court. As they navigate the treacherous political landscape, the four heroes must confront their own tragic pasts and personal demons. Their loyalty to the Emperor and their brotherhood is tested by betrayal, forbidden romances, and the machinations of powerful enemies who seek to destabilize the empire. The series blends high-stakes action with intricate character development, highlighting the struggle between justice and personal desire.