Golden lawyer Su Wan took over a serial murder case. The murderer would leave her business card at the scene every time he committed a crime. Police officer Lu Chen was ordered to investigate the case and suspected that Su Wan had some connection with the murderer. The two were forced to join forces to investigate, but found that the murderer's modus operandi was highly consistent with Lu Chen's "shadow personality" that had been missing for many years. When the truth gradually emerged, Su Wan discovered that she was not only the defense lawyer in the case, but also the "referee" carefully selected by the murderer - each business card was a declaration of war against Lu Chen, and the end point of this game was the dark past shared by the three of them.
