Over a period of time, a series of extremely cruel serial murders occurred in society. The murderer was not only ruthless, but also arrogantly left a "death notice" at the scene. The police were angered by the criminals who called themselves "dark men", so they quickly set up a special task force, and the serious and old-fashioned Han Hao (played by Li Mincheng) served as the team leader. After that, Luo Fei (played by Guo Jingfei), a criminologist with extremely high IQ but extremely poor character, Mu Jianyun (played by Gan Lu), a noble, cold and eloquent psychology expert, Yin Jian (played by Jing Chao), a handsome trace expert known as the "shame of the police", Liang Yin (played by Li Qian), a Gothic style forensic doctor, Zeng Rihua (played by Su Dan), a computer expert, and Xiong Yuan (played by Wang Jing), a terrifying criminal policeman whose legs and feet are ahead of his brain, joined the team one after another. This group of police eccentrics with full personalities and very awkward personalities will engage in a series of high-IQ contests with cunning criminals...