In a future human society, everyone lives in separate, underground rooms, where all their needs and wants are provided by “the Machine.” One day, a woman, Vashti, receives a call from her son Kuno asking her to visit him in person. She doesn’t see the point of visiting him, since they can communicate just as easily through the Machine. Kuno wants to visit the earth’s surface (which is now apparently incapable of supporting life), a desire that Vashti, who is perfectly content living underground with the aid of the Machine, doesn’t understand. Kuno criticizes Vashti for worshipping the Machine as if it were a divine being. Later, Kuno tells Vashti that he will not talk to her anymore until she comes to visit him. She reluctantly decides to travel on an air-ship to the other side of the world where her son lives.
Onboard the air-ship, Vashti is distressed by the need to talk to and touch other people, and she is entirely uninterested in the natural scenery below. When she arrives in her son’s room, angry at him for making her undergo such a worthless trip, he tells her that he has been threatened with “Homelessness”—a form of execution in which the victim is placed on the earth’s surface without protective equipment, killing them. Kuno tells Vashti the story of how he escaped to the earth’s surface through a ventilation shaft and stayed there for a short time, fascinated by the natural world around him, before being drawn back underground by the Machine’s Mending Apparatus. Feeling that her son’s deviations are unforgivable, Vashti leaves and rarely talks to him again.
In the following years, respirators (protective equipment) are abolished, making it impossible to visit the earth’s surface. Meanwhile, the Machine is increasingly worshipped as a god. Kuno calls Vashti and tells her that “the Machine is stopping,” a statement that makes no sense to her. Defects start to appear in the Machine’s system, such as flaws in the music, fruit, beds, and other objects that the Machine summons. These defects become worse as time goes on, sparking outrage and panic in the society. The Committee of the Machine reveals that the Mending Apparatus itself has been broken.
One day, the ultimate disaster strikes, and the Machine stops entirely. All lines of communication are cut, and the air and light start to dissipate, condemning all the people living underground to certain death. As Vashti watches the crowds of people dying around her, she reunites with Kuno. He says there is no hope for them, but there are still humans living above-ground—“the Homeless”—who will carry on after this calamity, now that humanity has learned its lesson about the Machine. Vashti realizes that her son has been right all along about the Machine’s destructive impact on humanity. Vashti and Kuno embrace as an air-ship crashes into the city, destroying it and killing them.
