In the future world of 1984, the world is divided up into three superstates—Oceania, Eurasia, and Eastasia—that are deadlocked in a permanent war. The superpowers are so evenly matched that a decisive victory is impossible, but the real reason for the war is to keep their economies productive without adding to the wealth of their citizens, who live (with the exception of a privileged few) in a state of fear and poverty. Oceania, made up of the English-speaking nations, is ruled by a group known simply as the Party, a despotic oligarchical collective that is ideologically very similar to the regimes in power in the other two superstates, though each claims that their system is superior to the others. The Inner Party, whose members make up 2% of the population, effectively govern, while the Outer Party, who number about 13% of the population, unquestioningly carry out their orders. The remaining 85% of the population are proles, who are largely ignored because they are judged intellectually incapable of organized revolt. In order to maintain its power, the Party keeps its citizens under constant surveillance, monitoring even their thoughts, and arresting and "vaporizing" individuals if they show signs of discontent or nonconformity. The Party's figurehead is Big Brother, whose mustachioed face is displayed on posters and coins, and toward whom every citizen is compelled to feel love and allegiance. Organized hate rallies keep patriotism at a fever pitch, and public executions of prisoners of war increase support for the regime and for the war itself.
Winston Smith, a quiet, frail Outer Party member who lives alone in a one-room flat in a squalid apartment complex called Victory Mansions, is disturbed by the Party's willingness to alter history in order to present its regime as infallible and just. A gifted writer whose job at the Ministry of Truth is to rewrite news articles in order to make them comply with Party ideology, Winston begins keeping a diary, an activity which is not illegal, since there are no laws in Oceania, but which he knows is punishable by death. Since every room is outfitted with a telescreen that can both transmit and receive sounds and images, Winston must be extremely careful to disguise his subversive activities. He imagines he is writing the diary to O'Brien, a charismatic Inner Party bureaucrat whom Winston believes is a member of a fabled underground counterrevolutionary organization known as the Brotherhood. Winston is also writing in order to stay sane, because the Party controls reality to the extent of requiring its subjects to deny the evidence of their own senses, a practice known as doublethink, and Winston knows of no one else who shares his feelings of loathing and outrage.
One day at work, a dark-haired girl whom Winston mistakenly suspects of being a spy for the Thought Police, an organization that hunts out and punishes unorthodox thinking (known as thoughtcrime), slips him a note that says "I love you." At first, Winston is terrified—in Oceania, individual relationships are prohibited and sexual desire forbidden even to married couples. However, he finds the courage to talk to the girl, whose name is Julia, and they begin an illicit love affair, meeting first in the countryside, then in the crowded streets, and then regularly in a room without a telescreen above the secondhand store where Winston bought his diary. The proprietor, Mr. Charrington, seems trustworthy, and Winston believes that he, too, is an ally because of his apparent respect for the past—a past that the Party has tried hard to eradicate by altering and destroying historical records in order to make sure that the people of Oceania never realize that they are actually worse off than their ancestors who lived before the Revolution.
Meanwhile, the lovers are being led into a trap. O'Brien, who is actually loyal to the Party, dupes them into believing he is a counterrevolutionary and lends them a book that was supposedly written by the exiled Emmanuel Goldstein, a former Party leader who has been denounced as a traitor, and which O'Brien says will initiate them into the Brotherhood. One night, the lovers are arrested in their hiding place with the incriminating book in their possession, and they learn that Mr. Charrington has all along been a member of the Thought Police.
Winston and Julia are tortured and brainwashed by O'Brien in the Ministry of Love. During the torture in the dreaded room 101, Winston and Julia betray one another, and in the process lose their self-respect, individuality and sexual desire. They are then released, separately, to live out their broken lives as loyal Party members. In the closing scene, Winston, whose experiences have turned him into an alcoholic, gazes adoringly at a portrait of Big Brother, whom he has at last learned to love.