At a tonsure ceremony, the abbot who's meant to perform the ritual attempts to assassinate the Prince of the Song Dynasty; Yeung Mau, Ngau Tai-Lik and Ma Chuen-Kung of the Phecda Bureau thwart the attempt just in time; a prisoner, Sou Fu, escapes.

While Sou Fu's case successfully draws to a close, Chuen-Kung asks Cheung-Sing to go back to the Phecda Bureau with them.

Pak-Nin deduces what fell could be a meteor, which is regarded as an omen; Nam-Tin is annoyed because he doesn't know how to report the news to the Emperor.

Someone who claims to possess the sulphur goes to the Phecda Bureau to turn himself in, but Pak-Nin believes that he is just a scapegoat; Cheung-Sing wants to meet Hung Fung, but is rejected; at the opening day of the Peach Blossom Grove, Sap-Kau delivers lavish gifts while Tao Fa is distributing flyers; Cheung-Sing and three colleagues investigate Chaoyang Peak and uncover a cannon, so Cheung-Sing suspects that the late Minister Yuen had a secret mission.

Though Pak-Nin claims that it's impossible to search for the suspect, Chan Chit-Wo, among the Dragon Gang, Cheun-Kung believes those who have been exposed to explosives for a long time must show a variety of abnormal symptoms; Field Officer Choi follows Chi-Sin and discovers that he has several of those symptoms.

With the Phecda Bureau discovering that Kwan Chiu made the poison, Cheun-Kung and the others go to arrest her.