Ti Hau is a pupil of Master Ti, a high-ranking member of a boxer clan during the time of the Boxer Rebellion (1899 – 1901). Ti Tan, is a Member of a competing boxer clan who has successfully trained his students to resist penetration from swords (Golden Bell), but sacrifices them by experimenting with techniques to resist bullets. This appalls his niece, Fang Shao Ching. Lei Ying can control subjects with a voodoo doll and ventriloquism. The Yi Ho Society Chief, Li, explains that Lei Kung, an old pugilist master who left to form another branch in Yunan, has dissolved that branch and gone into hiding. Lei Kung no longer believes that their martial arts skills can defeat the modern weapons used by the western colonialists. Chief Yi proclaims Lei Kung a traitor to their movement. The chief orders his execution, and claims he can be identified because he enjoys showing off his kung-fu skills.
In Guangdong/Yunan, Ti Hau makes inquiries into the whereabouts of Lei Kung at a popular inn. Also searching is Fang Shao Ching, disguised as a man, and Lei Ying. They are unaware of each other’s identities, but observe each other suspiciously. A flamboyant man also shows up and arouses suspicion. Ti Hau and Fang Shao Ching both suspect Lei Ying of being Lei Kung, and sneak into the attic above his room at the inn. They fight in the cramped space as Ti Tan walks into the room below, but he does not see them before they escape.
An old woodcutter, Yu, also arouses Ti Hau’s suspicion because of his great strength. Fang Shao Ching distracts Ti Hau and lures him away, and they fight again but must stop to hide from Ti Tan. Fang explains to Ti Hau that her and Ti Tan are also Yi Ho members sent to kill Lei Kung, but she maintains her male disguise.
Under Fang’s guidance, Lei Kung practices with his weapons. Ti Hau, who has been bedridden, sees him, but Lei Kung maintains his identity as the woodcutter Yu by saying that he only looks like Lei Kung, and must defend himself. They both discover that Fang is a woman. When Ti Hau regains his strength, he is grateful to Yu for taking care of him and is about to leave, but Ti Tan arrives. Fang and Ti Hau fight him before Yu, now at full power, engages him. He finally admits to everyone that he is Lei Kung, and declares that he has betrayed the Yi Ho society because he does not want to see all his young students die in a futile attempt to fight foreign modern guns and cannon. He disables Ti Tan, who admits defeat and leaves. Ti Hau feels betrayed and also leaves.
Lei Kung dresses in ceremonial garb and arrives at a temple with Ti Hau, Fang Shao Ching, and a full set of weapons. Lei Ying is waiting, and reveals his plan. He wanted Lei Kung to regain his expertise and kill the other assassins. Then Lei Ying could avoid fighting others and concentrate on Lei Kung, killing him and elevating his position in their clan and Yi Ho Society. After an 8-minute duel showcasing most of the 18 weapons and hand-to-hand combat, Lei Kung demonstrates that he could win if he wanted to. But instead, he leaves Lei Ying to his disgrace.