The opera opens in Victory Square, Airstrip One - the London of a not-too-distant future. A crowd is gathered for a blood-thirsty rally against the enemies of Oceania (chorus: "Hate! Hate! Hate!"). The assembled throng venerates the image of the Party's leader, Big Brother, which appears on a giant telescreen, and then takes up the national anthem ("All Hail Oceania!").
Winston Smith, a mid-level civil servant in the Ministry of Truth, has witnessed the scene and gives voice to his hatred of Big Brother and the madness of Doublethink - "War is Peace! Freedom is Slavery! Ignorance is Strength!" are recurring mottos flashed on the telescreen.
Back at his desk, Winston sets to his assigned tasks, which are delivered by a new office girl, Julia. His orders are to continually revise official records so that Big Brother and the Party are always on the correct side of history. Winston chats with his fellow workers, Parsons and Syme, both of whom relish their duties. Parsons extols Big Brother's provision of all that a citizen might desire, even though he asks Winston in vain for a sharp razor blade, while Syme describes his fondness for the malleability of Newspeak, the official Party language, in a virtuosic aria "The beauty of Newspeak, sir!" O'Brien, Winston's superior and an Inner Party member, arrives and questions Winston somewhat mysteriously about his loyalty to the Party.
At home that evening in his dreary flat, Winston sets out his thoughts in a newly purchased diary, careful to position himself outside the view of the omnipresent telescreen ("A place to think for myself"). He falls asleep, half drunk on Victory Gin, and awakes the next morning to the shrill commands of the Gym Instructress emanating from the telescreen ("Hands at sides, citizens!" a comic coloratura aria). Parsons and his children, enthusiastic members of the Young Spies, burst in on their way to Victory Square for the hanging of a Eurasian prisoner-of-war.
The crowd in Victory Square is milling about in anticipation of the afternoon's hate rally and hanging. Various groups are present: Prole Children reciting nursery rhymes ("London Bridge is broken down"), the Young Spies taunting and setting fire to an old beggar-woman ("Die, blind hag!"), a Pub Quartet singing a sentimental love song ("It was only an 'opeless fancy") and Julia leading the Junior Anti-Sex League in a militant parade ("We pledge our lives to chastity"). Just as the prisoner is hanged, a rocket bomb falls nearby and bodies litter the scene. As the crowd disperses, Winston limps away.
Winston stumbles upon the antique shop where he had purchased his forbidden diary. The kindly proprietor, Charrington, shows Winston a bedroom above the shop without a telescreen and the two reminisce vaguely about the city of old. After leaving the shop, Winston notices Julia, believing she is a member of the Thought Police sent to find him out. She runs offs but drops a piece of paper that says "I love you" and instructs Winston to meet her the next day in the belfry of an old church.
In the belfry, Winston and Julia embrace cautiously, and she relates her story, telling of her own disillusionment with the Party ("You hide what you have to"). They declare their love for each other in a duet ("Let darkness do what powers might") before being interrupted by the sudden appearance of O'Brien, who summons them to his flat the next evening.
In his sumptuous quarters, O'Brien turns off his telescreen and then reveals his purpose to Winston and Julia ("We live in a world of slogans and doubletalk"). He asks the lovers to join the Conspiracy against Big Brother and demands their absolute obedience. They agree, but only up to a point. Neither Winston nor Julia will pledge to abandon the other if so called upon. O'Brien accepts this and suggests they hide.
Relishing their privacy in the room above Charrington's shop, Winston and Julia wonder if they will be able to stay together and vow never to betray each other ("What happens in our hearts"). After a blissful night, they overhear a Prole Woman in the backyard singing an old melody ("Stars still hang in the sky") just before Charrington, now revealed to be an agent of the Thought Police, bursts in to arrest both Winston and Julia, who are beaten and dragged off.
Winston is alone in a stark, white waiting room, though he is soon joined by a Drunken Woman who flirts crudely with him ("Come, my pretty"). A group of male prisoners, including Syme and Parsons, enters the cell, each accused of Thoughtcrime and subject to the terrors of Room 101. O'Brien appears, flanked by guards, and it dawns on Winston that O'Brien has been working for the Thought Police all along.
Winston is taken to an examination room and strapped to a bed. O'Brien enters to preside over Winston's torture and "cure." Gradually, he breaks down Winston's resistance and describes how the Party seized control. He also reveals that Julia is being similarly tortured in another cell. An utterly exhausted Winston is left alone to hallucinate about his past in an anguished aria ("I remember the Golden Country"). He collapses and is ordered to Room 101.
O'Brien again oversees Winston's torture, now in Room 101, where prisoners are confronted with their greatest fear. O'Brien insists that Winston will finally be made to love Big Brother, and threatens him with something unendurable to Winston: rats. This is enough to break Winston, who cries out, "Set the rats on Julia!"
Some time later, Winston and Julia - both dead-eyed figures - meet by chance in the Chestnut Tree Café off Victory Square. With strains of a nostalgic cabaret song ("Remember when") filtering in from next door, the former lovers coldly acknowledge their betrayal of each other and part, knowing they may never meet again. Winston looks up at the telescreen, which has announced a great victory for Oceania, and for the first time declares his love for Big Brother. Around a transfixed Winston, life goes on in Victory Square and the Prole Woman appears to wash the Café's window, humming the same tender song once overhead by Winston and Julia.