When the Mongols invade Europe, they are defeated at Krakow for the first time after many victories. Kubilai (Ken Clark), the responsible commander, asks his emperor Genghis Khan for a second chance. Kubilai has two ideas how to avoid another defeat. First, he wants to eliminate Maciste (aka Hercules in the American dubbed version), the hero of the Polish people, played by Mark Forest. And then, Kubilai holds a prisoner who reveals an important secret: the princess and future queen of Poland lives in a village under false identity. The Mongols want to capture her, but of course, Maciste is a guardian to any maiden in distress...