Lin Tao (Li Xian), the captain of the Longfan City Criminal Police, and Qin Ming (Zhang Ruoyun), the chief of the Forensic Medicine Department, are old friends for many years. Qin Ming's assistant resigned because he could not stand Qin Ming's weird temper. Li Dabao (Jiao Junyan) from the Trace Inspection Department was seconded to join the working group. At first, Qin Ming did not trust Dabao, a girl, but the stubborn Dabao showed quite good reasoning and observation skills in solving the case, and her sense of smell was extremely sensitive. The picky Qin Ming decided to keep Dabao. The iron triangle of the Longfan Police Station was also formed. They cooperated with each other and solved various incredible cases one after another. This drama is adapted from Qin Ming's suspense mystery novel "The Eleventh Finger".