Chien Fu (Jackie Chan), an orphan adopted by a Chinese martial arts school, is overworked as their janitor and abused by the kung fu teachers as a walking punching-bag, with the school's cook, Ah-Wu (Tino Wong), being his only sympathizer. Chien befriends an old beggar (Yuen Siu Tien) by offering him a meal and a place to stay. Unknown to Chien, the old beggar is actually Pai Cheng-Tien, one of the last surviving masters of the Snake Kung Fu of Chinese martial arts. Pai is on the run from the Eagle Claw clan, which is viciously killing off all of the rival Snake-style masters, but is ambushed by Eagle Claw student Su Chen and an assassin masquerading as a Christian missionary (Roy Horan), and is injured. After being abused once more, Chien later finds Pai and helps him recover. Pai agrees to give him more lessons, on the condition that he does not call him "sifu" ("master"), since they are friends. The real reason, however, is to keep Chien's connection with him secret from his pursuers.