The story is set in Republican Shanghai when a series of murders throw the city into chaos. While investigating, private detective Chen Yi Ming (Wang Long Zheng) gets to know Zhang Tian Xiao (Ji Ning), the son of the police chief, as well as the beautiful Yao Fei (Gan Lu) who just returned from overseas. The three join hands in order to uncover the big conspiracy behind those murder cases.
The usually carefree Guan Hong Yu (Pan Yue Ming) gets accused of having murdered a whole family. To clear his younger twin brother’s charge, the team leader of the criminal investigation department Guang Hong Feng (Pan Yue Ming) wants to take on this case, but since he’s a relative, he’s not allowed to participate in the investigation. A new team leader named Zhou Xun (Wang Long Zheng) is assigned and ends up seeking Hong Feng’s help. Zhou Xun and Hong Feng as his “consultant” uncover a number of cases together. However, Hong Feng has a secret: one of the twin brothers has fear of the dark phobia, so the “Hong Feng” appearing at the police station during the day and at night is actually not the same person. Together, the twins secretely try to find out the truth about the “family extinction murder case”.