"It was a bright cold day in April, and the clocks were striking thirteen." The year is 1984... Maybe. All that's definitively understood is that we are on what used to be the British Isles, now known as Airstrip One, a few decades after a Revolution that took place during the global nuclear wars following World War II and left the world in the hands of three superpowers called Oceania, Eurasia, and Eastasia. Oceania has always been at war with Eurasia, or so everyone seems to remember; in reality, only four years ago Oceania was at war with Eastasia and in alliance with Eurasia... But in this world, reality is a very malleable concept.
As everyone in Oceania knows, there is only one Party and only one leader, the omnipresent godlike Big Brother. Oceania's rigid society is divided into the Inner Party, the ruling elite; the Outer Party, the lower government officials and bureaucrats, the closest thing there is to a middle class; and the 'proles', the poor and uneducated lower classes who make up the vast majority of the population, monitored for signs of unrest but otherwise left contemptuously alone ("proles and animals are free," runs the relevant Party slogan). Everyone is conditioned through a carefully manipulated mixture of fear and gratitude to love their leader, Big Brother, as their only protector against total chaos.
Opposition to the Party is discouraged by keeping everyone outside the Inner Party constantly on the brink of starvation and exhaustion. Any resultant discontent is easily answered since "there's a war on, after all." The proles are kept sedated with mindless entertainment and cheap booze, and the Outer Party members survive on a principle called 'doublethink' — a defense mechanism that consciously suppresses the idea that there might be any differences between the Party line and reality. There are no longer any laws, but everyone in the Party is hyper-aware that the faintest glimmer of discontent or even individualism, known as "thoughtcrime," might lead to becoming an "unperson", which is not only to be destroyed but to have one's life rewritten out of existence.
The Party's ideology, called Ingsoc, or English Socialism, has moved beyond the social experiments of past totalitarian regimes, and aims to completely reshape people's ability to perceive the world around them. History is continually rewritten -- often outright made up — by the Party so that Big Brother is always right, has always made the right predictions, and always implemented the right policies, for which the citizenry are always appropriately grateful. No evidence to the contrary, in any media, is allowed to remain. As part of this effort, a new language, Newspeak, is being constructed, with the express intent of removing all "superfluous" shades of meaning, especially concepts related to political freedom. The ultimate goal is the elimination of the ability even to think about an anti-authority concept, let alone express it in words.
Winston Smith, a seasoned member of the Outer Party, is also a secret rebel — although since his dreams of defiance are the mundane ones typical of the common man, they apparently haven't yet been discovered. What finally drives him over the edge into becoming the hero of our story is his constant, instinctive feeling that there must be more to life than the uniformly dull and dreary present and the nightmarish future. If the Party can constantly reshape the collective memory, including your very existence, on an ever-changing whim... What meaning is there in anything? As the novel opens, Winston commits a decisive act of thoughtcrime: Writing all of this down in a secret diary.
His heresy next expands to take in a boldly attractive, down-to-earth young woman named Julia, who one day passes him a note that changes his life: I love you. Sexually eager and shrewd in all the small day-to-day methods of rebellion, she joins him on secret trysts in an upstairs room he rents from what he thinks is a nice old pawnbroker. For a few months the lovers meet and live like a heartbreakingly teenage-like couple.
Partly through Julia's influence and partly out of his own fierce longing, Winston dares to hold on to the belief that the Party can somehow be toppled. The major hope lies in the Brotherhood, a rumored underground organization seeking to overthrow Big Brother. Winston's golden opportunity seems to come in the form of O'Brien, an extremely powerful member of the Inner Party who through various subtle signals to Winston appears to be harboring rebellious thoughts of his own. Alas, it's only a cruel delusion: Soon after Winston and Julia believe they have enlisted in the Brotherhood through O'Brien, it is revealed that the Party had known of their defection all along. They are arrested by the Thought Police and sent to the Ministry of Love.
Winston is imprisoned for weeks and then tortured by O'Brien, whose only loyalty turns out to be to the Party, into believing that two plus two make five and that Oceania has always been at war with Eastasia, because Big Brother says so. Gradually Winston becomes the perfect Big Brother devotee — on the outside at least; but still clinging desperately to the hope that "they can't get inside you." That spark is smashed out from him once and for all by a scarring visit to the dreaded Room 101, where his worst fear is cruelly used against him. He betrays Julia, and with that relinquishes the last of his humanity. After his public confession and release, while awaiting his inevitable execution, Winston realizes that he loves Big Brother.