Carthoris, Prince of Helium, sets out in his flyer to rescue the kidnapped Princess of Ptarth, having no knowledge of the evil he is up against. The villain Astok had been shrewd in his schemings, making it seem as though Carthoris himself had been Thuvia's abductor. ~ ~ Thus, even if Carthoris, half-Earthling, half-Martian, managed to find Thuvia and successfully fight off the murderous banths, deadly invisible bowmen, and the green giants, who would belive that he had not been the perpetrator of the crime?