NamTar, a geneticist known for his brutal but brilliant experiments, offers to provide star charts leading to the home worlds of D'Argo, Zhaan and Rygel in exchange for one of Pilot's four arms. However, when the charts are loaded into Moya, the data crystal overloads Moya's systems and all but one star chart must be removed to make Moya operational again. D'Argo, Zhaan and Rygel pit themselves against one another in a battle to decide which map stays. At the same time, Crichton battles NamTar to rescue Aeryn from the grasps of the evil scientist who has turned her into a host body for one of his deadly genetic experiments.