Equality 7-2521, a 21-year-old man writing by candlelight in a tunnel under the earth, tells the story of his life up to that point. He exclusively uses plural pronouns ("we", "our", "they") to refer to himself and others. He was raised like all children in his society, away from his parents in collective homes: the Home of Infants from birth until five years old, then the Home of Students from five to fifteen. He believes he has a "curse" that makes him learn quickly and ask many questions. He excels at the Science of Things and dreams of becoming a Scholar, but when the Council of Vocations assigns his Life Mandate at fifteen, he is assigned to be a Street Sweeper.
Equality 7-2521 accepts his street sweeping assignment as penance for his Transgression of Preference in secretly desiring to be a Scholar. He works with the handicapped Union 5-3992 and International 4-8818, the latter of whom is Equality 7-2521's only friend (which is another Transgression of Preference, because all are supposedly equal in their society). Despite International 4-8818's protests that any exploration unauthorized by a Council is forbidden, Equality 7-2521 explores an underground tunnel near the City Theatre tent, and finds metal tracks. Equality 7-2521 believes the tunnel is from the Unmentionable Times of the distant past. He begins sneaking away from his community at night to use the tunnel as a laboratory for scientific experiments, using garbage he has taken from the Home of the Scholars. He is using stolen paper from the Home of the Clerks to write his journal by candlelight, using candles stolen from the larder at the Home of the Street Sweepers.
While cleaning a road at the edge of the city, Equality 7-2521 meets Liberty 5-3000, a 17-year-old Peasant girl who works in the fields. He commits another transgression by thinking constantly of her, instead of waiting to be assigned a woman at the annual Time of Mating, in which men aged twenty and over, and women of eighteen and over, are assigned to each other solely for breeding. She has dark eyes and golden hair, and he names her "The Golden One". When he speaks to her, he discovers that she also thinks of him. He reveals his secret name for her, and Liberty 5-3000 tells Equality 7-2521 she has named him "The Unconquered".
Continuing his scientific work, Equality 7-2521 rediscovers electricity. In the ruins of the tunnel, he finds a glass box with wires that gives off light when he passes electricity through it. He decides to take his discovery to the World Council of Scholars; he thinks such a great gift to mankind will outweigh his many transgressions and lead to him being made a Scholar. However, one night, his absence from the Home of the Street Sweepers is noticed. He is whipped and held in the Palace of Corrective Detention. The night before the World Council of Scholars is set to meet, he easily escapes; there are no guards because no one has ever attempted escape before. The next day, he presents his work to the World Council of Scholars. Horrified that he has done unauthorized research, they assail him as a "wretch" and a "gutter cleaner" and say he must be punished. They want to destroy his discovery so it will not disrupt the plans of the World Council and the Department of Candles. Equality 7-2521 seizes the box, cursing the council before fleeing into the Uncharted Forest that lies outside the city.
In the forest, Equality 7-2521 sees himself as damned for having left his fellow men, but he enjoys his freedom. No one will pursue him into this forbidden place. He only misses Liberty 5-3000. On his second day of living in the forest, Liberty 5-3000 appears; she followed him into the forest and vows to stay with him forever. They live together in the forest and try to express their love for one another, but they lack the words to speak of love as individuals.
They find a house from the Unmentionable Times in the mountains and decide to live in it. While reading books from the house's library, Equality 7-2521 discovers the word "I" and tells Liberty 5-3000 about it. Her first words to him are, “I love you.” Having rediscovered individuality, they give themselves new names from the books: Equality 7-2521 becomes "Prometheus" and Liberty 5-3000 becomes "Gaea". Months later, Gaea is pregnant with Prometheus's child. Prometheus wonders how men in the past could have given up their individuality; he plans a future in which they will regain it.
