Winston Smith is a member of the Outer Party. He works in the Records Department in the Ministry of Truth, rewriting and distorting history. To escape Big Brother's tyranny, at least inside his own mind, Winston begins a diary — an act punishable by death. Winston is determined to remain human under inhuman circumstances. Yet telescreens are placed everywhere — in his home, in his cubicle at work, in the cafeteria where he eats, even in the bathroom stalls. His every move is watched. No place is safe.
One day, while at the mandatory Two Minutes Hate, Winston catches the eye of an Inner Party Member, O'Brien, whom he believes to be an ally. He also catches the eye of a dark-haired girl from the Fiction Department, whom he believes is his enemy and wants him destroyed. A few days later, Julia, the dark-haired girl whom Winston believes to be against him, secretly hands him a note that reads, "I love you." Winston takes pains to meet her, and when they finally do, Julia draws up a complicated plan whereby they can be alone.
Alone in the countryside, Winston and Julia make love and begin their allegiance against the Party and Big Brother. Winston is able to secure a room above a shop where he and Julia can go for their romantic trysts. Winston and Julia fall in love, and, while they know that they will someday be caught, they believe that the love and loyalty they feel for each other can never be taken from them, even under the worst circumstances.
Eventually, Winston and Julia confess to O'Brien, whom they believe to be a member of the Brotherhood (an underground organization aimed at bringing down the Party), their hatred of the Party. O'Brien welcomes them into the Brotherhood with an array of questions and arranges for Winston to be given a copy of "the book," the underground's treasonous volume written by their leader, Emmanuel Goldstein, former ally of Big Brother turned enemy.
Winston gets the book at a war rally and takes it to the secure room where he reads it with Julia napping by his side. The two are disturbed by a noise behind a painting in the room and discover a telescreen. They are dragged away and separated. Winston finds himself deep inside the Ministry of Love, a kind of prison with no windows, where he sits for days alone. Finally, O'Brien comes. Initially Winston believes that O'Brien has also been caught, but he soon realizes that O'Brien is there to torture him and break his spirit. The Party had been aware of Winston's "crimes" all along; in fact, O'Brien has been watching Winston for the past seven years.
O'Brien spends the next few months torturing Winston in order to change his way of thinking — to employ the concept of doublethink, or the ability to simultaneously hold two opposing ideas in one's mind and believe in them both. Winston believes that the human mind must be free, and to remain free, one must be allowed to believe in an objective truth, such as 2 + 2 = 4. O'Brien wants Winston to believe that 2 + 2 = 5, but Winston is resistant.
Finally, O'Brien takes Winston to Room 101, the most dreaded room of all in the Ministry of Love, the place where prisoners meet their greatest fear. Winston's greatest fear is rats. O'Brien places over Winston's head a mask made of wire mesh and threatens to open the door to release rats on Winston's face. When Winston screams, "Do it to Julia!" he relinquishes his last vestige of humanity.
Winston is a changed man. He sits in the Chestnut Tree Café, watching the telescreens and agonizing over the results of daily battles on the front lines. He has seen Julia again. She, too, is changed, seeming older and less attractive. She admits that she also betrayed him. In the end, there is no doubt, Winston loves Big Brother.