Astrogar Horpach and his deputy Rohan face a mystery when the intact "Condor" and the remains of its crew are discovered. There are no survivors, but food supplies, water, and oxygen reserves would have been sufficient for many months. However, the interiors of the spaceship are in an indescribable state, as if a horde of savages had taken residence inside. As the scientists from the "Invincible" determine, there is no hostile fauna or flora on Regis III, yet the planet is under the control of a force that nearly brings disaster to the rescue expedition.