As the representative of the ruthlessly ruling robotic brain over the vast empire of the Arkonides, Perry Rhodan must pay a visit to the planet Zalit. There, he encounters mysterious alien beings known as the Mooff. He follows the trail of horror and arrives at Nour, where the crew of his spaceship is afflicted by the terrible Nonus plague. Seven hundred people, including Thora, Bully, and many mutants, are threatened with death. Who are the mysterious masterminds behind all these events? The search for answers to all these questions ultimately leads Rhodan to Aralon, the center of galactic medicine. There, decisions are made not only about the lives and deaths of the sick space travelers but also about the fate of all humanity.