Criminal investigation captain Lu Chen pursues a series of serial murder cases in which the deceased had a strange "smile" on his face. Every time, he "picks up" Lin tide, a sugar girl who behaves strangely at the crime scene. Sometimes she looks like an innocent bystander, sometimes like a cold-eyed prophet, sometimes like... The murderer himself. During the pursuit and counter-pursuit, suspicion and temptation, the two were forced to join hands, but found that the case involved an unsolved case from seven years ago, as well as shadows within the police station.
