S hih Yen-ko, an eccentric swordsman (Wang Li), has vowed to kill any evil-doers on "Judgment Day" every three years, except for those whose clan chief stands forward on their behalf. He issues an edict entitling its finder to one favor. A young stranger Shih Chung-chien, nicknamed Son of a Bitch (Philip Kwok) acquires the edict by chance, but Shih snatches it back and teaches him a fatal type of kung fu with the intention of its killing him.

M eanwhile, Shih Chung-yu (Kuo Chue) is fleeing his Hsueh Shan clanmates after committing rape. His parents Shih Ching and Min Ju vow to deliver him up for punishment, not knowing he is now the Chief of the Chang Lo Clan. With Chung-yu missing, Chang Lo Clan head plots to have the insane Chung-chien, who resembles Chung-yu, pose as their Chief to avert Shih's massacre. Chung-chien is later palmed by a Hsueh Shan man who mistakes him for Chung-yu, but Chung-chien, dying of Shih's fatal kung fu instruction, revives and instead becomes a sophisticated martial artist. A girl named Ting Tang (Candy Wen Hsueh-erh) is also deceived and claims to be his fiancee, and her grandpa Ting San (Yang Chi-ching) insists on their getting married.

B ut Chung-chien is needed by Chang Lo Clan to go back to pose as Chief. Chung-chien is forced to face Shih and fight him on behalf of the clan. Eventually his true identity is discovered and traced back to his abduction as a baby.