The director of this movie Tsui Hark (Syu Ke) was the most ambitious director at the end of the 70s. He calls this movie to be a futuristic film; it does not follow the traditional way, which narrates a story chronologically, instead it switches the role of the main character, Hua Hongye, gradually from a narrator to a participator. This movie starts when Hua is invited to investigate a murder by the Master of Shenjia Bao, then he involves himself in this complicated case. He is an outsider, but from time to time he changes his role to become the center of this case. Doubling the role of Hua Hongye is a new technique for the director, who, also is the writer of the screenplay; he uses Hua Hongye to illustrate his thinking about the way of the martial arts circle.

      Hua Hongye known by his nickname as Hongye Shusheng (Hongye the intellectual) has a notebook, which is wanted by both the government side and the gang side because it records many mysterious cases occurring in the martial arts circle. One of the cases, a homicide case committed by the butterfly, is the topic of this movie.

      Hua along with two martial arts masters, Tian Fong and Cing Yingzih, is invited to the mansion, Shenjia Bao, to invest the butterfly-killing cases by the Master of the mansion Shen Cing. Shen Cing also becomes one of the victims of the butterfly after the invited three investigators came. Hua and the others want to start a detailed investigation, but the widow of Shen Cing stops them. She insists to wait until a group called Tianlei Sisiang, formed by four sworn brothers, come.

      Three members of the Tianlei Sisiang come, the youngest is said to have died, but an armored man kills the widow. Hua finds out that the armored man is actually Shen Cing who is not dead. This Shen Cing is also the youngest of the sworn brothers by the real name of Yun Jhen, as an imposter, who killed the real Shen Cing after his elder brothers asked him to come to steal a powerful new formula of gunpowder from Shen Cing. He did not want to share the formula with others so, apart from pretending to be Shen Cing, he schemed the butterfly killings. Finally he kills all his brothers before Hua Hongye leaves. He believes that he is the most powerful man in the martial arts circle, but Tian Fong, who did not leave with Hua, challenges him, and Tian kills him.

      Hua Hongye is depicted as an isolated person, who is famous in the martial arts circle for his fair investigating and recording of events. To him there is no right or wrong in the martial arts circle, but one power replaces the other in the name of revenge, and the strongest can never last for long.