On the planet Trinia, humans slaves are kept in the vast Mineworld at the center of the planet, herded by robot slaves and forced to dig crystals for the robot god Zygon. As he digs the young slave boy Orin unearths a sword hilt, whereupon a vision of an elderly man appears, telling him that his people really belong on the surface, that he, Orin, can lead them and free humanity from enslavement to the robots. Orin escapes to the surface where he befriends the smuggler Dagg Debrini and is thrown into a series of interglacatic adventures as he fights to bring down Zygon.