Chien Fu, an orphan raised in a kung fu school, works as its overworked janitor and endures daily abuse from the teachers who treat him like a walking punching-bag. His only source of warmth is Ah-Wu, the school’s cook, who offers a quiet moment of kindness amid the harsh routine. One day, he shares a meal and a place to stay with an old beggar, Pai Chang Tien, not realizing the man is one of the last Snake-style masters fleeing the ruthless Eagle Claw clan that hunts rival fighters. When Pai is ambushed by Su Chen and an assassin posing as a Christian missionary, he is badly wounded. After suffering abuse once more, Chien finds Pai and helps him recover, and Pai agrees to teach him more—on one condition: Chien must not call him “sifu” because they are friends, a stipulation that also keeps Pai’s presence hidden from his pursuers.
As Chien trains, he learns to dodge the school’s bumbling teachers and begins to master the Snake-style he’s learned from Pai. When the Mantis school invades the academy, Chien astonishes everyone by defeating their master with the snake method. A wandering witness to the fight, the high master of the Eagle Clan, Sheng Kuan, recognizes the style and starts tailing Chien, intrigued by this new contender.
Chien eventually crosses paths with [Sheng Kuan] in person, who inquires about the old beggar, claiming he was a colleague of Pai’s. To prove his claim, Chien’s defense is tested and he is forced to hold his own against the formidable intruder. Realizing that his Snake-style alone cannot match this stranger’s mastery, Chien is inspired to create a new approach after observing his pet cat kill a cobra, giving birth to a bold, fresh fighting system—the Cat Claw.
Meanwhile, the Eagle Claw conspirators close in on Pai, tracking him down until Pai finally exacts vengeance by killing [Su Chen]. Pai returns to Chien’s hiding place, but the danger isn’t over: Ah-Wu is revealed as an Eagle Claw conspirator, and he poisons their tea in a calculated betrayal.
Racing to warn Sheng Kuan, Chien and Pai find Pai forced to flee as pursuers close in. In the ensuing confrontation, Chien discovers the full truth behind the conspiracy only after defeating the disguised missionary, and he confronts Sheng Kuan in a climactic duel. Although initially disadvantaged, Chien unveils his new Cat Claw technique—an invention that even Sheng Kuan cannot counter—killing the Eagle master. Ah-Wu arrives and confirms his loyalty, but Chien and Pai feign defeat, fatally wounding Ah-Wu and avoiding the poison that had been intended for them. With the immediate threat ended, Chien and Pai walk away together to continue refining the new technique, giving it its name and preparing for whatever challenges lie ahead.
