Prime Minister Michael Callow faces a huge and shocking dilemma when Princess Susannah, Duchess of Beaumont, a much-loved member of the Royal Family, is kidnapped. For her safe return, the Prime Minister must have live sexual intercourse with a pig on national television, with a list of technical specifications designed to make it impossible to fake. Callow adamantly opposes fulfilling the demand and does all possible to catch the kidnapper before the deadline. Callow also demands the news not reach the public, but the ransom video has been posted on YouTube and, despite having only been up for nine minutes, has already been viewed and downloaded by many members of the British public. Although the UK's media initially agrees via a D-Notice not to report the story, it soon reaches foreign news networks, which immediately report. After this, the UK media follow suit. The public's response is initially one of sympathy towards Callow, and the majority do not expect him to go through with the demand. Twitter wags christen the incident hashtag #Snoutrage.

When the British government first receives the video, the Home Secretary, Alex Cairns attempts to manufacture fake footage to broadcast (via using highly sophisticated technology to place the PM's head onto a willing surrogate who would perform in his stead). The kidnapper discovers the ploy and sends Princess Susannah's finger to a UK news station as a response. The story is outed and public opinion turns sharply against Callow; a majority now demand he follow through with the kidnapper's ransom although his wife Jane begs him not to go through with it. This drives Callow to order an immediate rescue operation on the building where they believe Susannah is being held, forgoing the recommended observation period. The building is revealed to be a decoy and a reporter is injured during the operation. Callow loses even more support.

After being informed that his party, the public and the royal family are demanding he fulfills the ransom demand and neither he nor his family will have protection from repercussions if he refuses, Callow performs the act in front of a live global audience who are quickly disgusted by the sight but still continue watching. The Princess is discovered unharmed in the streets, the finger having belonged to the kidnapper. It is revealed that she was released before the deadline, but went unnoticed as everyone was distracted by the broadcast. It emerges that Turner Prize winner Carlton Bloom planned the events, intending to make an artistic point by showing events of significance slipped under the noses of the public and the government as they were "elsewhere, watching screens" and not paying attention to the real world. Bloom commits suicide as the broadcast airs, and it is decided that the early release will not be revealed to anyone including Callow.

A year after the broadcast, Callow's political image has remained intact and gained greater public approval due to his willingness to sacrifice his dignity. Princess Susannah has recovered from the kidnapping and is expecting a child, while the public at large knows of Bloom's organising of the affair and have for the most part moved on from the incident. While Callow's reputation has been raised in the eyes of the public, it is implied that his relationship with Jane has not survived the ordeal—a year after the incident, she is shown making a public appearance with him, but is entirely cold to him in private.

In a bedroom, a woman named Victoria Skillane wakes up in a chair to find she can't recall anything about her life. Apparently the result of a failed suicide attempt, Victoria is surrounded by images of a small girl whom she assumes to be her daughter—as well as photos of her and an unknown man. Victoria sees an unusual symbol on the TV screens in the house and a calendar on the month of October, with all the dates being crossed off up until the 18th. Leaving the house, Victoria sees people constantly recording her on their phones. She first asks for help and then shouts at the people to stop recording her, but all ignore her until a man wearing a balaclava with the symbol on it pulls up in a blue Rolls Royce, takes out a shotgun, and fires at Victoria. After being chased by the masked man, she meets Jem and Damien, who are gathering supplies. The masked man kills Damien, who attempted to save Victoria and Jem, forcing them to flee. Jem explains that a mysterious signal began appearing over television and the internet, turning most of the population into dumb voyeurs who do nothing but record everything around them. Victoria and Jem are unaffected, but are also a target for the 'hunters', unaffected humans who—with society's collapse—can act violent and sadistic without repercussions. Jem plans to reach a nearby transmitter at 'White Bear' to destroy it and stop the signal's effect on the area.

As they travel, a man named Baxter picks up Victoria and Jem. Baxter is also unaffected, but drives them to a forest and holds them at gunpoint, revealing that he was the masked man from earlier. Although Jem escapes, Victoria is tied to a tree and about to be tortured until Jem returns and kills Baxter. They continue traveling to the transmitter, while Victoria has visions of past and future events. When they reach the White Bear transmitter to destroy it, two hunters attack Victoria and Jem. Victoria wrestles a shotgun away from a hunter and fires at her attacker, only for it to spray confetti.

The walls open to reveal an audience applauding after observing the escapade; Jem, Damien, and the hunters are revealed to have been actors in a kind of real-world play. Victoria is strapped to a chair, and Baxter appears and explains everything: the girl Victoria assumed was her daughter was actually six-year-old Jemima Sykes, whom Victoria and her fiancé, Iain Rannoch (the man from the photographs), abducted a few miles from her home. After taking her to a nearby forest, Iain tortured and killed Jemima and burned her body while Victoria recorded his actions on her mobile phone. The "White Bear", originally the victim's stuffed teddy bear, became a symbol of the nationwide search and murder investigation, while the symbol on the screens and on the hunter's mask was identical to the tattoo that identified Victoria's fiancé (who committed suicide in his cell before the trial). Having tearfully pleaded guilty and insisting she was "under Iain's spell", Victoria was given a sentence the judge described as "proportionate and considered": to undergo an experience where she would feel the same feelings of terror and helplessness that the victim did, repeated every day.

Victoria, who still has no clear memory of these events, is driven back to the compound past a crowd baying for her blood (under encouragement from the staff) and returned to the room where she woke up. She is placed back in the bedroom chair by Baxter. As she is shown footage of Jemima, Baxter places electrodes on her head, wiping Victoria's memory of the day's events as she screams in agony. As Baxter leaves the compound to the sound of Victoria's screams, he takes out a black pen and crosses off 18 October from the calendar, getting ready for Victoria to relive the same events the next day.