民国时期上海动荡不安，巡捕高官郭先生离奇死亡。私家侦探陈一鸣受到郭太太的委托，调查郭先生遇害一案。陈一鸣来到凶案现场勘查，并猜测凶手的具体特征，同时推断这是一起谋杀案。陈一鸣前去询问戏班班主，偶然发现戏班里的赵明若跟凶手的特征十分相似。陈一鸣再次来到戏班想去瞧瞧赵明若，谁知赵明若竟然死了。警察把陈一鸣抓了起来，怀疑他是杀死赵明若的凶手。
During the Republic of China, Shanghai was in turmoil, and Mr. Guo, a senior patrol official, died mysteriously. Private detective Chen Yiming was entrusted by Mrs. Guo to investigate the murder of Mr. Guo. Chen Yiming came to the scene of the murder to investigate, guessed the specific characteristics of the murderer, and concluded that this was a murder. Chen Yiming went to ask the theater leader and accidentally discovered that Zhao Mingruo in the theater had very similar characteristics to the murderer. Chen Yiming came to the theater again to see Zhao Mingruo, but Zhao Mingruo died. The police arrested Chen Yiming and suspected that he was the murderer of Zhao Mingruo.
