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.
Jan awakes one early morning and looks at the moon. To his surprise, it has started rotating—the children are testing their power. Soon, the Overlords tell him, the Overmind will arrive and assimilate the children into itself. The Overlords must leave, but Jan chooses to stay. Karellen asks Jan to record the transmogrification of the children as they join the Overmind. As Jan watches, a great, misty web appears across the sky. The children's bodies begin to disappear, and soon the very Earth itself becomes transparent as the children draw on it for energy. The Earth's core explodes, and the children feed on every last atom of its mass.
Karellen watches from his ship as the last remnants of Earth vanish from the solar system. A sadness fills him, for he knows his race will never achieve what he has just seen happen to man. But with a patient resolution, he continues to do the Overmind's work, hoping to some day decipher its secrets.
Jan's trip to the Overlord homeworld has a very interesting literary parallel, although it does not occur to Jan and may or may not have been in the mind of Arthur C. Clarke. It is significant that the world Jan visits is not the Overlords' homeworld; it is a world that they have colonized and made into their base of operations. So, their situation is that they are demonic-looking slaves of a higher power, who have made a "heaven of hell" by transforming a world into their home. This is reminiscent of the first part of Paradise Lost, where Satan and his demons create the city of Pandemonium in Hell. With its demons flying through the streets and buildings, the Overlord city that Jan sees could easily be substituted for Pandemonium. Add to that the subservient position of the Overlords to the Overmind, like Satan to God, and the Overlords' inability to join the Overmind—much like Satan and the rebel angels are denied the Divine Presence—and the parallels become obvious. Karellen himself might be seen as Satan, meddling in the affairs of men at the behest of the Overmind, much like God allows Satan to test Job's piety and fitness for Heaven.
Childhood's End concludes with a science fiction version of Armageddon. Mankind has not only been eliminated by the Overmind; the entire Earth is destroyed and consumed for its mysterious purposes. As discussed in the analysis of previous chapters, the conclusion of Childhood's End is perhaps the most controversial ending of any story by Arthur C. Clarke, and it is certainly what makes Childhood's End so unique and enduring in the public imagination. Despite the many flaws of the story, both in its ideas and in the way the story is told, there is something timeless about the notion of humanity moving forward toward a kind of evolutionary nirvana, a stage at which the mind is no longer tied to the body and existence is at the level of pure thought.
However, this ending, while occurring on a science fiction novel, should be recognized for what it is: a very mystical event that probably has more in common with Revelations than with a scientific textbook. In a novel where there are aliens that look like the Devil, a cataclysmic event like the transformation of the children and the destruction of Earth must be looked from a mythological as well as a scientific perspective. One of Clarke's most famous quotes is that, "any sufficiently advanced technology is indistinguishable from magic." However, there is nothing technological about the Overmind or its assimilation of humanity. Even the Overlords, those masters of science and reason, admit that the Overmind is beyond their understanding, and they suspect it always will be. But, as the Overlords admit, the Overmind is not omnipotent. It needs the Overlords' help, and it apparently fears what would happen if a race scientifically studied extra-sensory perception and other mental faculties on its own. There is a curious dichotomy here: the Overmind is beyond the limited understanding of humans and even the Overlords, yet it requires the aid of the Overlords to achieve its goals.
As mentioned in previous analyses, there is something vaguely sinister and tyrannical about the Overmind. The conclusion of Childhood's End is anticlimactic and perhaps depressing. Humanity has lost all characteristics of itself within the collective thing known as the Overmind. Uniqueness and individuality are lost forever. Jan claims that the end of humanity "repudiates optimism and pessimism alike." More significantly, Jan, who has seen the stars, agrees that they are "no place for man." This is anathema to Arthur C. Clarke and his beliefs, and this may be why Clarke added the warning, "The opinions expressed in this book are not those of the author" to the paperback edition. In the universe of Childhood's End, humans are not a race in and of itself, but just another larval nest of the Overmind. This is an interesting but ultimately bleak perspective, removing all uniqueness and significance from humanity in favor of a transcendental, mystical apocalypse.