1984

In a dystopian 1984, Winston Smith (John Hurt) endures a squalid existence in the totalitarian superstate of Oceania under the constant surveillance of the Thought Police. The story takes place in London, the capital city of the territory of Airstrip One (formerly "either England or Britain").
Winston works in a small office cubicle at the Ministry of Truth, rewriting history in accordance with the dictates of the Party and its supreme figurehead, Big Brother. A man haunted by painful memories and restless desires, Winston is an everyman who keeps a secret diary of his private thoughts, thus creating evidence of his thoughtcrime.
His life takes a major turn when he is accosted by a fellow Outer Party worker â a mysterious, bold-looking girl named Julia (Suzanna Hamilton) â and they begin an illicit affair. Their first meeting takes place in the remote countryside where they exchange subversive ideas before having sex. Shortly after, Winston rents a room above a pawn shop (in the supposedly safe proletarian area) where they continue their liaison. Julia â a sensual, free-spirited young woman â procures contraband food and clothing on the black market, and for a brief few months they secretly meet and enjoy an idyllic life of relative freedom and contentment together.
It comes to an end one evening, with the sudden raid of the Thought Police. They are both arrested and it's revealed that there is a telescreen hidden behind a picture on the wall in their room, and that the charmingly old-fashioned and seemingly sensitive proprietor of the pawn shop, Mr. Charrington (Cyril Cusack), is a covert agent of the Thought Police. Winston and Julia are taken away to the Ministry of Love to be detained, questioned and "rehabilitated" separately. There O'Brien (Richard Burton), a high-ranking member of the Inner Party whom Winston had previously believed to be a fellow thought criminal and agent of the resistance movement led by the archenemy of the Party, Emmanuel Goldstein, systematically tortures him.
O'Brien instructs Winston about the state's true purpose and schools him in a kind of catechism on the principles of doublethink â the practice of holding two contradictory thoughts in the mind simultaneously. For his final rehabilitation, Winston is brought to Room 101, where O'Brien tells him he will be subjected to the "worst thing in the world", designed specifically around Smith's personal phobias. When confronted with this unbearable horror â which turns out to be a cage filled with wild rats â Winston's psychological resistance finally and irretrievably breaks down, and he hysterically repudiates his allegiance to Julia. Now completely subjugated and purged of any rebellious thoughts, impulses, or personal attachments, Winston is restored to physical health and released.
In the final scene, Winston returns to the Chestnut Tree CafÃ©, where he had previously seen the rehabilitated thought criminals Jones, Aaronson and Rutherford (themselves once prominent but later disgraced members of the Inner Party) who have since been "vaporized" and rendered unpersons. While sitting at the chess table, Winston is approached by Julia, who was similarly "rehabilitated". They share a bottle of Victory Gin and impassively exchange a few words about how they have betrayed each other. They act indifferently towards each other. After she leaves, Winston watches a broadcast of himself on the large telescreen confessing his "crimes" against the state and imploring forgiveness from the populace.
Upon hearing a news report declaring the Oceanian army's utter rout of the enemy (Eurasian)'s forces in North Africa, Winston looks at the still image of Big Brother that appears on the telescreen, then turns away and almost silently says "I love you" â a phrase that he and Julia repeatedly used during their relationship, indicating the possibility that he still loves Julia. However, he could also be declaring his love for Big Brother instead, as in the book.[note 2]

Question: What was the unbearable horror?
Answer: A cage filled with rats