Chien Fu, an orphan who is taken in by a kung fu school, endures a hard life as their janitor and a constant target of abuse from the teachers, his body used as a walking punching bag while the school's cook Ah-Wu remains his only genuine ally. In a quiet act of kindness, Chien offers a meal and a place to rest to an old beggar, not knowing that this bedraggled visitor is Pai Cheng-tien, one of the last surviving masters of the Snake-style of kung fu. Pai is fleeing the ruthless Eagle Claw clan, which is methodically wiping out rival Snake-style masters. Their fragile peace is shattered when Pai is ambushed by Su Chen, an Eagle Claw student, and a disguised assassin posing as a Christian missionary, leaving him badly injured. After another brutal night of abuse, Chien eventually finds Pai and helps him recover, and a wary trust begins to form between them. Pai agrees to teach Chien again, but with a crucial caveat: Chien should not call him sifu, or master, because their bond is meant to be one of friendship and secrecy from those who would hunt Pai.
As Chien trains, he learns to adapt and defend himself against the school’s bumbling instructors, turning each harsh encounter into a lesson. The life of the school takes a sensational turn when the Mantis school invades, and to everyone’s astonishment, Chien defeats their master using the Snake-style he has learned, a feat witnessed by a passing wanderer. This observer, Sheng Kuan, the high master of the Eagle Clan, recognizes the distinctive style immediately and intents to tail Chien to uncover the source of this power. Chien’s path crosses with Sheng Kuan’s when they meet, and Sheng Kuan performs a display of skill that instantly reveals Chien’s limitations against a true master of a rival style. Realizing his Snake-style is no match for the newcomer, Chien watches a cat kill a cobra and is inspired to conceive something new.
This turning point drives Chien to experiment further with the ideas borrowed from the animal kingdom, and he builds a fresh approach to combat—one that blends cunning, agility, and an unexpected lineage of moves. Later, the Eagle Claw conspirators close in on Pai, pressing him to reveal where he has hidden his knowledge. Pai manages to kill Su Chen in a dramatic confrontation, and he returns to hide with Chien. Yet danger continues to loom, as Ah-Wu is revealed to be an Eagle Claw conspirator who has poisoned their tea, threatening to expose them both and their alliance.
Chien rushes to find Sheng Kuan, only to witness Pai flee as danger closes in; the chase intensifies, and secrets behind the conspiracy gradually emerge as Chien defeats the fake missionary and uncovers the wider web of intrigue. The moment of reckoning comes when Pai and Chien confront Sheng Kuan in single combat. Though Pai’s warnings and the odds seem stacked against them, Chien finds his footing, drawing on the new techniques he has developed. He unveils his ultimate response with a fighting style he has named after the very creature that sparked his breakthrough—the Cat Claw—a technique that Sheng Kuan finds almost unbearable to counter, ultimately leading to Sheng Kuan’s defeat.
The fight ends with Ah-Wu’s arrival, where his true allegiance is finally laid bare. Chien and Pai, feigning defeat, turn the tide on their would-be betrayer and fatally wound Ah-Wu, just as they realize they have somehow avoided ingesting the poison they were tricked into consuming. With the immediate danger behind them, Chien and Pai reflect on their narrow escape and decide to walk a new path together. They set off into the distance, intent on refining the Cat Claw technique and giving it its rightful name, a symbol of their unlikely alliance and the resilience born from hardship. This marks not just an end to the immediate conflict, but the beginning of a fresh chapter in Chien’s journey as a fighter who crafts his own destiny from adversity and observation.
