The plot centers on a masked martial artist known as Iron Monkey. Iron Monkey is actually the alter ego of a traditional Chinese medicine physician called Yang Tianchun. In the day, Yang runs his clinic and provides free medical treatment for the poor, which he subsidises by charging his rich patients. At night, he dresses in black and travels around town to rob the rich and help the poor. Once, he breaks into the governor's residence and makes off with a hoard of gold. The guards and four Shaolin Monastery monks are unable to stop him. The governor orders the chief constable, Fox, to hunt down Iron Monkey and to arrest anyone who is linked to him in any way. Fox appears to be a bungler who is not aware that Iron Monkey is actually the physician treating his injured men who fought with Iron Monkey the previous night.