Brave New World is considered one of the greatest works of science fiction ever written, and the first several chapters of the novel are spent worldbuilding so that the reader will understand how this brave new world operates. Fittingly, the first chapter opens with a guided tour of the Central London Hatchery and Conditioning Centre, where the Director of Hatcheries and Conditioning is leading a group of young students through the building, explaining the more complicated science that the author, Aldous Huxley, has invented for the novel. During this tour, the reader learns that everyone in this civilization is a clone, the product of Bokanovsky's Process, which takes a single fertilized egg, arrests the development, and then forces it to bud or split, creating up to ninety-six viable embryos, which in turn create ninety-six identical twins. This homogenization process has been perfected for the purpose of creating order in the world. Their world motto is "Community, Identity, Stability."
To maintain that stability, the World Controllers have devised a system wherein different classes of people (Alphas, Betas, Gammas, Deltas, and Epsilons) correspond to different levels of power, intellect, and wealth, with Alphas at the top with the best jobs and Epsilons at the bottom with all the grunt work. They're been conditioned to accept their station through an elaborate, systematic brainwashing process that involves sleep teaching, electric shocks, and explosions. Everyone, the Director says, is conditioned to hate nature but to love playing sports in the country, which World Controllers find productive because it stimulates the economy. All these decisions are made by a group of ten people, including one Mustapha Mond, the Resident Controller for Western Europe, whom we'll get to know later in the novel.
During this long tour, the reader is introduced to two of the main characters of the novel: Bernard Marx, an Alpha-Plus with a reputation for being antisocial, and Lenina Crowne, his love interest, whom he'll briefly date. In an awkward scene in an elevator, Lenina approaches him in front of a former conquest of hers, Benito Hoover, and asks Bernard if he still wants to take her away for a vacation in New Mexico. He gets flustered, which is considered strange in this society, then goes to talk to his friend Helmholtz, a screenwriter for the "feelies" (what they call the movies). Their vacation won't come until two chapters later, in Chapter 6, and in the meantime Lenina goes on a date with Henry, another suitor of hers, according to the dictum that "every one belongs to every one else" and that nobody should practice monogamy. Bernard is somewhat uncomfortable with this, which leads to trouble in both his personal and professional life.
Before he goes to New Mexico, he happens to speak with his boss, the Director, who threatens to banish him to Iceland (where some of the people who question authority are sent) if he makes so much as one more mistake at work. During this brief conversation, the Director tells Bernard that he went to New Mexico, too, once, and that he lost his girlfriend in the desert and left her behind. This foreshadows a scene in Chapter 7 when Bernard and Lenina, during their visit to the savage reservation, meet a young man named John and his mother, Linda, the woman the Director left in the desert. John is their son, born and raised on the reservation and taught to read out of a volume of The Complete Works of William Shakespeare, and, because of this, his emotional development has been stunted, making him incapable of understanding the true complexities of Shakespeare's work, which in turn leads to violent and dramatic outbursts. He falls in love with Lenina without even getting to know her.
Bernard decides to bring Linda and John back to London with him in order to embarrass his boss "Tomakin" (Thomas), the Director, who resigns in disgrace after John calls him Father in front of a roomful of people. This brings both Bernard and John notoriety, and they become very popular at parties and other upper caste gatherings for a while, even as Linda slips into a near-vegetative state due to overuse of soma, the drug people take every day in this novel to relax. Buoyed by his newfound popularity, Bernard begins dating, sometimes seeing upwards of six women a week. In the meantime, John is introduced to the civilized world, touring various factories and schools and growing increasingly bitter about the state of the world. He is, however, still in love with Lenina, and they begin dating in Chapter 11.
Through his relationship with Lenina and his friendship with Helmholtz, whose determination to be a real artist has led to him clashing with his bosses, John is briefly able to withhold his disdain for this brave new world; and then, just as quickly as their relationship began, it ends, when John realizes that Lenina isn't as pure as he thought and becomes so violent (yelling that she's a whore and pushing her away) that she has to lock herself in the bathroom. She's still hiding there when John gets a phone call saying that his mother is ill and in the hospital. He rushes to her side and, in his grief, upsets a group of young Deltas who are in the middle of being desensitized to death. He makes one of the little boys cry, leading the nurses and the hospital staff to think he's going mad. Helmholtz, having been informed of this by a friend, rushes over, hoping to keep John from doing something drastic. In the end, he, John, and Bernard are all arrested for throwing soma out of the hospital windows (though, as Bernard insists, he wasn't involved in that).
The three are taken to meet Mustapha Mond, the Resident World Controller for Western Europe, who has a long philosophical discussion with John about what constitutes happiness, then reveals that he, too, was a dissenter, and that his scientific research was once so radical that he was given a choice: either stay and be given immense power and authority or leave and live in Iceland with other like-minded people, rebels like John and Helmholtz. He stayed, and now it's in his power to send people like him away—Bernard to Iceland and Helmholtz to the Falkland Islands. After the others are taken away, John and Mustapha Mond are left to talk about God and suffering. John is determined to suffer, and Mustapha Mond decides to send him somewhere he can do that alone.
In the final chapter, John goes to live in an old lighthouse in a forgotten part of England. He lives there in peace for a little while before the reporters and tourists inevitably find him, and then he's surrounded by gawkers who all watch in amazement as he whips himself with knotted cords. He doesn't understand why they won't leave him alone, and he lashes out at them, whipping a young woman who reminds him of Lenina. This violence leads to a kind of orgy in which John, having somehow taken or been given soma, loses himself in a "frenzy of sensuality." The next morning, horrified by what has happened, John hangs himself in the lighthouse. The novel ends when, that evening, the reporters return to find his body swaying gently from the rafters.