It is the late twentieth century. For years, the Soviet Union and the United States have been in a race to create the first spaceship with a nuclear drive. Reinhold is the main scientist for the U.S.; Konrad Schneider is the USSR's specialist. However, just as both scientists are poised for success, giant alien spaceships appear from the skies and land over every major world city.
The first chapter takes place five years after the prologue. The Overlords, as the humans call the aliens, have "conquered" all of Earth and set about instituting many new changes. For six days after their arrival, the ships had hovered over the cities, watching the worlds' reaction. On the sixth day, the voice of the being that humans would come to call the Supervisor, Karellen, was relayed across every radio frequency. Speaking perfect English, Karellen informed all of Earth that its affairs were being taken over. Instantly, nations realized their sovereignty was at an end. One superpower attempted to destroy a rival by firing a nuclear missile at an Overlord ship, but the missile had simply vanished into thin air. Only one government had refused to submit to the admittedly fair demands of the Overlords. The Republic of South Africa would not end its policy of discrimination, so the Overlords mysteriously blocked out the sun for half an hour. Afterward, no further demonstrations of power were needed. From then on, life steadily improved for all of humanity throughout the world, as the Overlords effected their changes.
While most of the Overlords' commands are transmitted through text messages, the Earth does have one personal liaison to Karellen: Stormgren, the Secretary- General of the United Nations. As the chapter begins, Stormgren is about to meet with Wainwright, a clergyman and the leader of the Freedom League, an organizatio that opposes the domination of the Overlords, despite the Overlords' so-far friendly attitude. The Freedom League objects to the "coddling" of the Overlords, meddling in human affairs. They don't like the idea of the World Federation, the Overlords' plan for a world government. Even more importantly, they object to the fact that the Overlords will not reveal what they look like. Even Stormgren, who has met with Karellen for years, has never actually seen him. Stormgren agrees to address the League's concerns at his next meeting with the Supervisor.
Stormgren accordingly visits Karellen soon after. He is taken up in a tiny, egg- shaped ship to Karellen's ship, which hovers fifty kilometers over New York. Karellen already knows all about the interview with Wainwright, because the Overlords have spying devices all over Earth. Karellen banters with Stormgren, and points out that men like Wainwright fear Karellen because he is a powerful threat to the world's religions. He knows that they wonder how long the Overlords have been watching mankind, and whether they know the truth behind Buddha, Christ and Muhammed. As for revealing himself, Karellen tells Stormgren that he will consult his superiors and ask for permission.
Childhood's End was developed from one of Clarke's earlier short stories, "Guardian Angel." The main conceit of both "Guardian Angel" and the first half of Childhood's End is taking the old cliché of the "alien invasion" and turning it on its head. The Overlords don't start blowing up every Earth capital. Instead, they use their power to stop governments from fighting among themselves. The Overlords work to end war, disease, and hunger, and raise the standard of living for everyone on Earth. The primary method of achieving this is the discreet but firm use of power. Tasks like absorbing nuclear missiles without so much as an explosion and blotting out the sun present few difficulties to the Overlords but still have a maximum effect. Neither results in a loss of human life. The theory used by the Overlords is actually somewhat similar to the idea of deterrence used in the Cold War between the United States and the Soviet Union. The giant nuclear missiles built by both countries were not intended to ever be fired, though they were capable of it; they were intended only to deter the other superpower from attempting to attack. The Overlords work the same way: they make their vast powers known so the humans don't make any foolish moves, but they do not intend to use that power to create human suffering.
However, both violent and beneficent "invasions" are still invasions, and Wainwright and his Freedom League are representative of that. One of the themes of Childhood's End is the question of freedom and what it entails. Regardless of how much better the Overlords make things for humans, they are basically coddling humanity. With their displays of power, the Overlords cow humanity into a form of submission. Admittedly, it's the most pleasant form of submission possible; as the novel progresses, life on Earth comes closer and closer to a utopia. But even utopias have their limitations, particularly in keeping the populace from being bored. But regardless of boredom, it is very likely that humans would become restless in a utopia (as Jan Rodricks does later in the novel). But the problems of a utopian society become more important later in the book. "Guardian Angel," the short story upon which Childhood's End is based, is less concerned with the creation of a utopian society as it is with humanity's desire to see what Karellen and his fellow Overlords look like. For reasons unknown to both the characters and the reader at this early point in the novel, Karellen refuses to reveal the physical appearance of the Overlords. This refusal is a key issue for the Freedom League; it is difficult to trust the Overlords, despite all their actions, without having seen them.