A crooked martial arts school recruits a cadre of specialist fighters to massacre a rival school. Jimmy Wang Yu plays the titular boxer, who escapes the massacre but not before losing his right arm. After convalescing, Wang Yu takes a mysterious elixir that grants his remaining arm superhuman strength. He then sets out for revenge.

Despite the well-worn plot, the execution surprises. The early battles prove competent if unremarkable save some outdoor locales. But things veer toward bonkers when the foreign specialist fighters arrive. Each employs a distinct style. The judo master executes joint locks and throws. The Thai boxers pummel their opponents with vicious knees and elbows. The Taekwondo expert delivers powerful chops and kicks. The Tibetan monks inflate their bodies to form a protective armor. The Indian yoga expert—played by a Chinese actor in blackface—dizzies his opponent by running around in handstand circles. And the dreaded karate master—who sports a set of tusk-like fangs the film never explains—severs limbs with a single blow.

These fighters slaughter Wang Yu’s school in a memorable sequence, leaving lone survivor Wang Yu crawling away with a bloody stump in place of his severed right arm. A medicine man and his attractive daughter find Wang Yu and nurse him back to health. The bonkers cranks up another notch with the miracle elixir, which requires Wang Yu to kill the nerves in his good arm before ingestion. Cue a montage delivered in Sam Raimiesque dutch zooms of Wang Yu punching fiery coal pits and smashing his remaining arm with a levered boulder.

Soon Wang Yu returns to exact revenge with his new super arm. The film achieves bonkers escape velocity with the finale. Set in a canyon with the rival school boss and henchman watching from on high, Wang Yu disposes of the specialists one by one. When he faces the Indian yoga expert, who assumes his signature handstand position, Wang Yu assumes a one-armed handstand. The yoga master runs at Wang Yu on his hands. Wang Yu, still in a one-armed-handstand, pops up on two fingers and runs at the yoga master. The rival school henchman gives his boss a look that says, “We’re in trouble.”

Yet, despite this insanity, the revenge-based narrative stakes still resonate, priming the final showdown between Wang Yu and the fanged karate master with anticipation. Like the rest of the film, it doesn’t disappoint.