While searching another planet, Buck and Twiki locate the remaining survivors of a colonization attempt. Most of the colony members had left years earlier because of an unknown plague. Two of the survivors, a young widow named Cyra (Anne E. Curry) and her son Delph (Robert Lane), stayed behind to run their farm. While there, they are continually attacked by a horned creature named Pangor, yet Syra refuses Buck's invitation to leave, which Buck cannot understand. Before he can convince them to abandon the planet, Buck is stricken by the plague, which begins to transform him into a creature known as a "Satyr".