Brave New World opens in the Central London Hatching and Conditioning Center, where the Director of the Hatchery and Henry Foster are giving a tour to a group of boys. The boys learn about the Bokanovsky Process, which allows the Hatchery to produce thousands of nearly identical human embryos. During the gestation period the embryos travel in bottles along a conveyor belt through a large factory building, and are conditioned to belong to one of five castes: Alpha, Beta, Gamma, Delta, or Epsilon. The Alpha embryos are destined to become the leaders and thinkers of the World State. Each of the succeeding castes is conditioned to be slightly less physically and intellectually impressive. The Epsilons are destined to perform menial labor.
The Director then leads the boys to the Nursery, where they observe a group of Delta infants being reprogrammed to dislike books and flowers. The Director explains that this conditioning helps to make Deltas docile and eager consumers. He then tells the boys about the " " (sleep-teaching) methods used to teach children the morals of the World State. In a room where older children are napping, a whispering voice is heard repeating a lesson in "Elementary Class Consciousness".
Outside, the Director shows the boys hundreds of naked children engaged in sexual play and games like "Centrifugal Bumble-puppy". Mustapha Mond, one of the ten World Controllers, introduces himself to the boys and begins to explain the history of the World State. Meanwhile, inside the Hatchery, Lenina Crowne chats in the bathroom with Fanny Crowne about her relationship with Henry Foster. Fanny chastises Lenina for going out with Henry almost exclusively for four months, and Lenina admits she is attracted to the strange, somewhat funny-looking Bernard Marx.
In another part of the Hatchery, Bernard is enraged when he overhears a conversation between Henry and the Assistant Pre destinator about "having" Lenina. After work, Lenina tells Bernard that she would be happy to accompany him on his trip to the Savage Reservation in New Mexico. Bernard flies a helicopter to meet a friend of his, Helmholtz Watson. He and Helmholtz discuss their dissatisfaction with the World State.
Bernard is primarily upset because he is too small and weak for his caste; Helmholtz is unhappy because he is too intelligent for his job writing phrases. In the next few days, Bernard asks his superior, the Director, for permission to visit the Reservation. The Director launches into a story about a visit to the Reservation he had made with a woman twenty years earlier, in which, during a storm, the woman was lost and never recovered. Finally, he gives Bernard the permit, and Bernard and Lenina depart for the Reservation. Before heading into the Reservation, Bernard calls Helmholtz and learns that the Director has grown weary of what he sees as Bernard's difficult and unsocial behavior and is planning to exile Bernard to Iceland when he returns. Bernard is angry and distraught, but decides to head into the Reservation anyway.
On the Reservation, Lenina and Bernard are shocked to see its aged and ill residents; no one in the World State has any visible signs of aging. They witness a religious ritual in which a young man is whipped, and are disgusted. After the ritual they meet John, a fair-skinned young man who is isolated from the rest of the village. John tells Bernard about his childhood as the son of a woman named Linda who was rescued by the villagers some twenty years ago, and Bernard realizes that Linda is the woman mentioned by the Director. Talking to John, he learns that Linda was ostracized because of her willingness to sleep with all the men in the village, and that as a result John was raised in isolation from the rest of the village. John explains that he learned to read using two books, one called The Chemical and Bacteriological Conditioning of the Embryo, and the other titled The Complete Works of Shakespeare, the latter given to Linda by one of her lovers, Pop'e.
John tells Bernard that he is eager to see the "Other Place" - the "brave new world" that his mother has told him so much about. Bernard invites him to return to the World State with him. John agrees but insists that Linda be allowed to come as well. While Lenina, disgusted with the Reservation, takes enough soma to knock her out for eighteen hours, Bernard flies to Santa Fe where he calls Mustapha Mond and receives permission to bring John and Linda back to the World State. Meanwhile, John breaks into the house where Lenina is lying intoxicated and unconscious, and barely suppresses his desire to touch her. Bernard, Lenina, John, and Linda fly to the World State, where the Director is waiting to exile Bernard in front of his Alpha coworkers, but before he can, Bernard turns the tables by introducing John and Linda.
The shame of being a "father" causes the Director to resign, leaving Bernard free to remain in London. John becomes a hit with London society because of his strange life led on the Reservation. But while touring the factories and schools of the World State, John becomes increasingly disturbed by the society that he sees. His sexual attraction to Lenina remains, but he desires more than simple lust, and he finds himself terribly confused.
In the process, he also confuses Lenina, who wonders why John does not wish to have sex with her. As the discoverer and guardian of the "Savage", Bernard also becomes popular, and he quickly takes advantage of his new status, sleeping with many women and hosting dinner parties with important guests, most of whom dislike Bernard but are willing to placate him if it means they get to meet John. One night John refuses to meet the guests, including the Arch-Community Songster, and Bernard's social standing plummets. After Bernard introduces them, John and Helmholtz quickly take to each other. John reads Helmholtz parts of Romeo and Juliet, but Helmholtz cannot keep himself from laughing at a serious passage about love, marriage, and parents-ideas that are ridiculous and obscene in World State culture. Fueled by his strange behavior, Lenina becomes obsessed with John, refusing Henry's invitation to see a feel.
She takes soma and visits John at Bernard's apartment, where she hopes to seduce him. But John responds to her advances with curses, blows, and lines from Shakespeare. She retreats to the bathroom while he fields a phone call in which he learns that Linda, who has been on permanent soma-holiday since her return, is about to die. At the Hospital for the Dying he watches her die while a group of lower-caste boys receiving their "death conditioning" wonder why she is so unattractive.
The boys are simply curious, but John becomes enraged. After Linda dies, John meets a group of Delta clones who are receiving their soma ration. He tries to convince them to revolt, throwing the soma out the window, and a riot results. Bernard and Helmholtz, hearing of the riot, rush to the scene and come to John's aid.
After the riot is calmed by police with soma vapor, John, Helmholtz, and Bernard are arrested and brought to the office of Mustapha Mond. John and Mond debate the value of the World State's policies, John arguing that they dehumanize the residents of the World State and Mond arguing that stability and happiness are more important than humanity. Mond explains that social stability has required the sacrifice of art, science, and religion. John protests that, without these things, human life is not worth living. Bernard reacts wildly when Mond says that he and Helmholtz will be exiled to distant islands, and he is carried from the room. Helmholtz accepts the exile readily, thinking it will give him a chance to write, and soon follows Bernard out of the room.
John and Mond continue their conversation. They discuss religion and the use of soma to control negative emotions and social harmony. John bids Helmholtz and Bernard good-bye. Refused the option of following them to the islands by Mond, he retreats to a lighthouse in the countryside where he gardens and attempts to purify himself by self-flagellation. Curious World State citizens soon catch him in the act, and reporters descend on the lighthouse to film news reports and a feel. After the feel, hordes of people descend on the lighthouse and demand that John whip himself.
Lenina comes and approaches John with her arms open. John reacts by brandishing his whip and screaming "Kill it! Kill it!" The intensity of the scene causes an orgy in which John takes part. The next morning he wakes up and, overcome with anger and sadness at his submission to World State society, hangs himself.