In a poverty-stricken and corrupt Qing Dynasty China, a Robin Hood-like vigilante known as the Iron Monkey has been stealing from the wealthy to help the poor. Dr. Yang, a kind physician, runs a clinic by day and becomes the elusive Iron Monkey by night. He is a master of martial arts, and his actions aim to counterbalance the injustices brought on by the government. Governor Cheng, the oppressive local governor, is intent on capturing this mysterious figure that undermines his tyrannical authority and embarrasses his regime.

Governor Cheng's efforts intensify when he apprehends Wong Kei-ying, a renowned martial artist, and his son Wong Fei-hung. Kei-ying is wrongly accused of being the Iron Monkey and is imprisoned, with his release conditioned on the capture of the true masked hero. While Kei-ying grapples with the dilemma and an underlying drive for justice, his son Fei-hung, demonstrates a prodigious martial arts talent and an inherent sense of righteousness. Their personal struggle becomes entangled with the fate of the Iron Monkey, as the lines between ally and enemy begin to blur among the rooftops and alleyways of the troubled city.