The dying master of the powerful Poison Clan dispatches his last pupil, Yang Tieh, on a crucial mission. Worried that the skills he has taught are being used to evil ends, he orders Yang to trace a retired colleague, Yun, and warn him that the fortune he amassed from the clan's activities is under threat from five of his former pupils, each an expert in his own lethal combat style. Yang must discover the whereabouts and true identities of these masked warriors, and decide which, if any, he can trust to join him in his mission. The five pupils are the Centipede, Snake, Scorpion, Lizard, and Toad. Centipede and Snake, and Lizard and Toad know each other, but none know the Scorpion, who always wears a mask. Before he dies, the master teaches Yang the weaknesses of each style.
The Centipede and the Snake come to the Yun family house to steal money. They murder the entire family when Yun refuses to divulge the location of his fortune. A witness sees the Centipede at the house. Later, the Scorpion investigates the scene and retrieves a hidden map. The Lizard, working as a policeman, recruits the Toad to help arrest the Centipede. After the Centipede is arrested and charged with murder, the Scorpion tells the Snake to frame the Toad for the murders. The corrupt judge sends the Lizard away on government business. The Snake pays an officer to make the witness commit perjury. The Toad is framed by the witness, who tells the judge that he saw the Toad at the scene of the crime. Toad refuses to confess, and his kung fu initially makes him invulnerable to their torture. The Scorpion devises a torture device to counteract it. When this fails, he cripples the Toad with darts to his weak spot. Subjected to further torture, the Toad passes out, and his signature is forged on a confession.
The Centipede is acquitted of the murder charges and goes free. The officer suffocates the Toad and hangs him in the cell as if he committed suicide. The Centipede and Snake kill the witness and the corrupt officer. Two Chinese policemen in the restaurant tell the Lizard what happened to the Toad, the witness, and the officer while he was gone. The Lizard's supervisor, Chief Constable Ma, encourages him to forget the issue, but the Lizard refuses. Yang identifies the Lizard, teams with him, and together they practice techniques to defeat the others. As Yang and the Lizard prepare to confront the Centipede and the Snake, the chief constable joins them. During the fight, he reveals himself as the Scorpion and reveals that he intends to kill everyone and keep the Yun fortune for himself. The Scorpion fatally injures the Snake and bribes the Centipede into helping him. Yang and the Lizard defeat the Centipede, and the Snake helps kill the Scorpion before he, too, dies. Yang and the Lizard retrieve the Scorpion's map from his corpse, vowing to use the fortune for good to restore the reputation of the Poison Clan.
Who finds a map?
The Scorpion