A tragic case of exterminating a family has turned Guan Hongyu, who was originally free and unrestrained, into a wanted suspect on the run. As the captain of the criminal investigation detachment, his twin brother Guan Hongfeng vowed to find out the truth, but due to the principle of relative avoidance, the police force prohibited Guan Hongfeng from participating in the investigation of the case of exterminating the family. Guan Hongfeng resigned in indignation. Zhou Xun, who was transferred to the acting detachment captain, was under pressure to solve the case. In order to track down Guan Hongyu's whereabouts, he designed to let Guan Hongfeng, who had resigned, continue to participate in the investigation of major major cases as an "extra-staff consultant." And everyone in the police force was kept in the dark. Suffering from "dark phobia", the "consultant Guan Hongfeng" who appeared in the police force during the day and at night was actually played by the twin brothers Bai Ye. The two brothers with different personalities kept making mistakes in the police force and were in danger of being discovered by Zhou Xun and various people at any time. They solved various major cases along the way. The purpose was just to wait for an opportunity to read the case files of the extermination case to find out the truth and clear their name...