Joan Vail is the Terrestrial paramour of a man named Greg Zhor. Zhor is a member of copper-skinned The Rihns, a peaceful people descended from the aboriginal Martians and the first terrestrials from Earth to settle on Mars. Because of Karragon, Tryant of Mars, spreading animosity between the Terrestrials against the Rihns, Joan and Greg are arrested by Karragon's Thelist Storm Guards. They are put to forced labor as punishment for their forbidden relationship. Joan is forced to work the looms in the great mills of Mercis. Zhor is sent to the moon of Phobus to work in the radium mine.