The novel is set in A.F. 632, approximately seven centuries after the twentieth century. A.F. stands for the year of Ford, named for the great industrialist Henry Ford who refined mass production techniques for automobiles. World Controllers rule the world and ensure the stability of society through the creation of a five-tiered caste system. Alphas and Betas are at the top of the system and act as the scientists, politicians, and other top minds, while Gammas, Deltas, and Epsilons are at the bottom and represent the world's industrial working class. A drug called soma ensures that no one ever feels pain or remains unhappy, and members of every caste receive rations of the drug. Pre- and post-natal conditioning further ensures social stability.
Brave New World opens with the Director of the Central London Hatchery and Conditioning Centre giving a group of young students a tour of the facilities. An assembly line creates embryos using the latest advancements in science. The students view the various techniques for producing more babies and watch as the process segregates babies into various castes. After the babies are decanted from their bottles, they are conditioned through Neo-Pavlovian conditioning and hypnopaedia. In Neo-Pavlovian conditioning, babies enter a room filled with books and roses. When the babies approach the books or the roses, alarms and sirens sound, and the babies receive a small electric shock, which frightens them so that when they confront the same items for a second time, they recoil in fear. Hypnopaedia teaches babies and children while they are asleep by playing ethical phrases numerous times so that the phrases will become a subconscious part of each person.
The World Controller of Western Europe, His Fordship Mustapha Mond appears and gives the students a lecture about the way things used to be. Before the Utopian world order was established, he explains that people used to be parents and have children through live birth. This existence led to dirty homes with families where emotions got in the way of happiness and stability. The first world reformers tried to change things, but the old governments ignored them. War finally ensued, culminating in the use of anthrax bombs. After the so-called Nine Years' War, the world suffered through an economic crisis. Exhausted by their disastrous living conditions, people finally allowed the world reformers to seize control. The reformers soon eradicated religion, monogamy, and most other individualistic traits, and they stabilized society with the introduction of the caste system and the use of soma.
Bernard Marx is introduced as a short, dark haired Alpha who is believed to have accidentally received a dose of alcohol as a fetus on the assembly line. His coworkers dislike him and talk about him in derogatory tones. Bernard has a crush on Lenina Crowne, another Alpha, and she informs the reader that he asked her to go with him to the Savage Reservations several weeks earlier. Lenina has been dating Henry Foster for the past several months, but since long-term relationships are discouraged, she agrees to go with Bernard Marx to the Reservations.
Bernard goes to Tomakin, the Director, and gets the Director’s signature to enter the Reservations. The Director tells a story about how he went there twenty-five years earlier with a woman. During a storm, she became lost, and circumstances forced him to leave her there. The Director then realizes he should not have told Bernard this story and defensively begins to yell at him. Bernard leaves unruffled and goes to talk to his good friend Helmholtz Watson about his meeting with the Director.
Helmholtz Watson is an intellectually superior Alpha who has become disillusioned with the society. He is tired of his work, which consists of writing slogans and statements to inspire people. Helmholtz indicates that he is searching for a way of expressing something, but he still does not know what. He pities Bernard because he realizes that neither of them can completely fit into the society.
Bernard flies with Lenina to the Savage Reservations. While there he realizes he left a tap of perfume running in his room, and so he calls Helmholtz Watson to ask him to turn it off. Helmholtz tells him that the Director is about to transfer Bernard to Iceland because Bernard has been acting so antisocial lately.
Bernard and Lenina enter the compound and watch the Indians perform a ritualistic dance to ensure a good harvest. A young man named John approaches them and tells them about himself. He was born to a woman named Linda who had been left on the Reservation nearly twenty-five years earlier. John is anxious to learn all about the Utopian world. Linda turns out to be the woman that the Director took to the Reservation and left there. She was unable to leave because she became pregnant with John, and since the Utopian society finds the notion of live birth disgusting, mothers and children are taboo topics.
Bernard realizes that John and Linda could save him from a transfer to Iceland. He calls Mustapha Mond and receives approval to bring them back to London. When Bernard finally returns, he has to meet with the Director in public. The Director publicly shames him and informs Bernard that he must go to Iceland. Bernard laughs at this and introduces Linda and John. At the disclosure of his past, the Director is so humiliated that he resigns. Bernard becomes an overnight celebrity due to his affiliation with John Savage, whose good looks and mysterious past make him famous. Reveling in his sudden popularity, Bernard starts to date numerous women and becomes extremely arrogant.
Bernard eventually hosts a party with several prominent guests attending. John refuses to come and meet them, which embarrasses Bernard in front of his guests. The guests leave in a rage while Bernard struggles to make amends. John is happier afterwards because Bernard must be his friend again.
Helmholtz and John become very good friends. Helmholtz has gotten into trouble for writing a piece of poetry about being alone and then reading it to his students. John pulls out his ancient copy of the Complete Works of Shakespeare and starts to read. The fiery passion of the language overwhelms Helmholtz, who realizes that this is what he has been trying to write.
Lenina has developed a crush on John the Savage, and she finally decides to go see him. After a few minutes, he tells her that he loves her. Lenina is very happy to hear this and strips naked in front of him in order to sleep with him. Immediately taken aback, John becomes extremely angry with her. Crying, "Strumpet!" he hits her and chases her into the bathroom. Fortunately for Lenina, a phone call interrupts John and he rushes off.
John goes to the hospital where Linda has finally succumbed to taking too much soma. While he tries to visit her, a large group of identical twins arrives for their death conditioning. They notice Linda and comment on how ugly she is. John furiously throws them away from her. He then talks to Linda, who starts asking for Pope, an Indian she lived with back on the Reservation. John wants her to recognize him and so he starts to shake her. She opens her eyes and sees him but at that moment, she chokes and passes away. John blames himself for her death. The young twins again interrupt him, and he silently leaves the room.
When he arrives downstairs, John sees several hundred identical twins waiting in line for their daily ration of soma. He passionately thinks that he can change the society and tells them to give up on the soma that is poisoning their minds. He grabs the soma rations and starts to throw the soma away. The Deltas get furious at this and start to attack him. Bernard and Helmholtz receive a phone call telling them to go to the hospital. When they arrive and find John in the middle of a mob, Helmholtz laughs and goes to join him. Bernard stays behind because he fears the consequences.
All three men are taken to meet Mustapha Mond who turns out to be an intellectual. He tells Bernard and Helmholtz that they must go to an island where other social outcasts are sent. The island is for people who have become more individualistic in their views and can no longer fit in with the larger society.
John and Mustapha engage in a long debate over why the society must have its current structure. John is upset by the regulation and banning of history, religion, and science. Mustapha tells him that the society’s design maximizes each person's happiness. History, religion, and science only serve to create emotions that destabilize society and thus lead to unhappiness. In order to ensure perfect stability, each person receives conditioning and learns to ignore things that would lead to instability. John continues protesting. The climax of the book comes when Mustapha tells John, "You are claiming the right to be unhappy." Mustapha then mentions a long list of mankind's ills and evils. John replies, "I claim them all."
Mustapha sends Bernard and Helmholtz away to an island, but refuses to allow John to leave. He tells John that he wants to continue the experiment a little longer. John runs away from London to an abandoned lighthouse on the outskirts of the city, where he sets up a small garden and builds bows and arrows. To alleviate his guilty conscience over Linda’s death, John makes a whip and hits himself with it. Some Deltas witness him in self-flagellation, and within three days, reporters show up to interview him. He manages to scare most of them away. However, one man catches John beating himself and films the entire event. Within a day hundreds of helicopters arrive, carrying people who want to see him beat himself. John cannot escape them all. Lenina and Henry Foster also arrive and when John sees Lenina, he starts to beat her with the whip. The crowd soon begins to chant “Orgy-porgy,” a sensual hymn used to generate a feeling of oneness. John loses himself within the crowd and wakes up the next day after taking soma and engaging in the sensual dance of the hymn. He is overwhelmed with guilt and self-hatred. That evening he is found dead in the lighthouse as he hangs from an archway.