Jan Rodricks is returning home to Earth, eighty years after he left. When he had first snuck out of his hiding place on the Overlord ship, the Overlords had not been particularly interested in him. Once arriving on the Overlord homeworld, he was locked in a room for several days until Vindarten, an Overlord who could speak English, took responsibility for Jan. Jan was then subjected to a number of tests, mostly psychological or mental in nature. Eventually, he was allowed to explore the city. The Overlord planet was not their original world. It was larger than Earth, so in order for their wings to work, the Overlords had altered the gravity of the world. The city is designed for people with wings. The design of the city is bleakly functional; they apparently lack any real artistic flair. They take Jan to a museum, where he sees many alien creatures, including the gigantic eye of a dead, cyclopean beast—an eye the size of a football field.
One strange thing Jan sees is a giant mountain, almost like a volcano. As he watches, strange colors thread around the mountain, and a ring of blue energy coalesces around the base and lifts off into the sky. Vindarten refuses to explain what this mountain is, but the narrator implies that this is an avatar of the Overmind.
In the present, the ship continues to approach Earth. To his surprise, Jan realizes that there are no lights on any of the continents. When he lands, only Karellen is waiting for him.
Karellen explains what happened after the great announcement that humanity was coming to an end. He shows Jan videos of the children as they developed their powers. For some time, they limp about like savages until they begin to develop vast mental powers. At the same time, their faces become blank, as their individuality is eaten away. Slowly they stop moving, as their bodies become less and less important. They start altering the surface of the earth, destroying plants, animals, mountains and anything else, just to exercise their powers.
Jan now sees the universe for what it is. There are two possibilities for any race. One is the seemingly close-ended path of the Overlords: supreme intellectual and technological achievement but still ultimately trapped in bodies with emotions and individuality. Like humans, their minds, despite how powerful they are, cannot grasp the infinite complexities of the universe. On the other hand, there is the Overmind, which works toward a complete awareness of everything in the universe but demands the loss of the individual and the eradication of the body in order to achieve its transcendental purposes.
Rashaverak cannot offer many answers to Jan, but he does reveal one thing: why the Overlords look so much like the Devil. The reason is not, as many humans had guessed, that the Overlords had visited Earth in the past. Instead, it was a kind of collective precognition: the human race had a vague premonition, a foreshadowing, of its ultimate demise, and a creature looking like the Devil would be involved. That creature was Karellen, the Overlord.