Genius student Xu Lang who specializes in Criminal Psychology obtained a Ph.D. at the University of Maryland. After returning to China, he joins the public security bureau but is severely injured and even loses his younger brother while solving a case. Seven years later, Xu Lang is the youngest professor of Criminology at the National Police University. Then, his friend Tang Sen invites him to return to the field and help out their newly established “Criminal Psychology Team X”. Together, the team of four uncovers unsolved cases and also finds new clues in Xu Lang’s life-changing case from seven years ago.

本剧讲述了宜庆市公安局犯罪心理四人小组，利用犯罪心理和高智商刑侦手段，破获悬案，探寻真相的故事。主人公徐朗通过对人面部表情和身体动作的观察，探测人们说谎背后的原因。面对一桩桩的离奇罪案，他和其他小组成员在不断磨合中日益强大，他们运用专业知识，挖掘犯罪心理、洞悉犯罪动机，从而预测罪犯的下一步行为，协助重案组侦破最棘手的案件。