This drama tells the story of the four-member criminal psychology team of the Yiqing Public Security Bureau, who use criminal psychology and high-IQ criminal investigation methods to solve unsolved cases and explore the truth. The protagonist Xu Lang detects the reasons behind people's lies by observing their facial expressions and body movements. Faced with a series of bizarre crimes, he and other team members are becoming stronger through constant running-in. They use their professional knowledge to explore criminal psychology and understand criminal motives, thereby predicting the criminals' next behavior and helping the serious case team solve the most difficult cases.