Fahrenheit 451 takes place in a dystopic America where Guy Montag is "fireman"--a burner of books for an oppressive regime. For many years, books were condensed and summarized due to shortening attention spans, and were finally banned. Montag begins to secretly steal books from his work and read them. After his wife snitches on him, he is forced to burn his house and run away with other readers. After the city is destroyed in a nuclear war, Montag and his group return to the city to build anew.
Fahrenheit 451 is set in an unspecified city (likely in the American Midwest) at an unspecified time in the future after the year 1960.
The novel is divided into three parts: "The Hearth and the Salamander", "The Sieve and the Sand", and "Burning Bright".
Guy Montag is a "fireman" employed to burn the possessions of those who read outlawed books. He is married but has no children. One fall night while returning from work, he meets his new neighbor, a teenage girl named Clarisse McClellan, whose free-thinking ideals and liberating spirit cause him to question his life and his own perceived happiness. Montag returns home to find that his wife Mildred has overdosed on sleeping pills, and he calls for medical attention. Mildred survives with no memory of what happened. Over the next days, Clarisse faithfully meets Montag as he walks home. She tells him about how her interests have made her an outcast at school. Montag looks forward to these meetings, and just as he begins to expect them, Clarisse goes absent. He senses something is wrong.
In the following days, while at work with the other firemen ransacking the book-filled house of an old woman before the inevitable burning, Montag steals a book before any of his coworkers notice. The woman refuses to leave her house and her books, choosing instead to light a match and burn herself alive. Montag returns home jarred by the woman's suicide. While getting ready for bed, he hides the stolen book under his pillow. Still shaken by the night's events, he attempts to make conversation with Mildred, conversation that only causes him to realize how little he knows her and how little they have in common. Montag asks his wife if she has seen Clarisse recently. Mildred mutters that she believes Clarisse died after getting struck by a speeding car and that her family has moved away. Dismayed by her failure to mention this earlier, Montag uneasily tries to fall asleep. Outside he suspects the presence of "The Hound", an eight-legged robotic dog-like creature that resides in the firehouse and aids the firemen.
Montag awakens ill the next morning and stays home from work. He relates the story of the burned woman to an apathetic Mildred and mentions perhaps quitting his work. The possibility of becoming destitute from the loss of income provokes a strong reaction from her, and she says the woman herself was to blame because she had books. Captain Beatty, Montag's fire chief, personally visits Montag to see how he is doing. Sensing Montag's concerns, Beatty recounts how books lost their value and where the firemen fit in: over the course of several decades, people embraced new media, sports, and a quickening pace of life. Books were ruthlessly abridged or degraded to accommodate a short attention span while minority groups protested over the controversial, outdated content perceived to be found in books. The government took advantage of this, and the firemen were soon hired to burn books in the name of public happiness. Beatty adds casually that all firemen eventually steal a book out of curiosity; if the book is burned within 24 hours, the fireman and his family will not get in trouble.
After Beatty has left, Montag reveals to Mildred that over the last year he has accumulated a stash of books that he has kept hidden in their air-conditioning duct. In a panic, Mildred grabs a book and rushes to throw it in their kitchen incinerator; Montag subdues her and tells her that the two of them are going to read the books to see if they have value. If they do not, he promises the books will be burned, and all will return to normal.
While Montag and Mildred are perusing the stolen books, a sniffing occurs at their front door. Montag recognizes it as The Hound while Mildred passes it off as a random dog. They resume their discussion once the sound ceases. Montag laments Mildred's suicide attempt, the woman who burned herself, and the constant din of bombers flying over their house taking part in a looming war neither he, nor anybody else, knows much about. He states that maybe the books of the past have messages that can save society from its own destruction. The conversation is interrupted by a call from Mildred's friend, Mrs. Bowles, and they set up a date to watch the "parlor walls" (large televisions lining the walls of her living room) that night at Mildred's house.
Montag, meanwhile, concedes that he will need help to understand the books. Montag remembers an old man named Faber he once met in a park a year ago, an English professor before books were banned. He telephones Faber with questions about books, and Faber soon hangs up on him. Undeterred, Montag makes a subway trip to Faber's home along with a rare copy of the Bible, the book he stole at the woman's house. Montag forces the scared and reluctant Faber into helping him by methodically ripping pages from the Bible. Faber concedes and gives Montag a homemade ear-piece communicator so he can offer constant guidance.
After Montag returns home, Mildred's friends, Mrs. Bowles and Mrs. Phelps, arrive to watch the "parlor walls". Not interested in this insipid entertainment, Montag turns off the walls and tries to engage the women in meaningful conversation, only to find them indifferent to all but the most trivial aspects of the upcoming war, friends' deaths, their families, and politics. Montag leaves momentarily and returns with a book of poetry. This confuses the women and alarms Faber, who is listening remotely. Montag proceeds to recite the poem Dover Beach , causing Mrs. Phelps to cry. At the behest of Faber in the ear-piece, Montag burns the book. Mildred's friends leave in disgust, while Mildred locks herself in the bathroom and takes more sleeping pills.
In the aftermath of the parlor party, Montag hides his books in his backyard before returning to the firehouse late at night with just the stolen Bible. He finds Beatty playing cards with the other firemen. Montag hands Beatty a book to cover for the one he believes Beatty knows he stole the night before, which is unceremoniously tossed into the trash. Beatty tells Montag that he had a dream in which they fought endlessly by quoting books to each other. In describing the dream Beatty reveals that, despite his disillusionment, he was once an enthusiastic reader. A fire alarm sounds, and Beatty picks up the address from the dispatcher system. They drive in the firetruck recklessly to the destination. Montag is stunned when the truck arrives at his house.
Beatty orders Montag to destroy his own house, telling him it was Mildred and her friends who reported him. Montag tries to talk to Mildred as she quickly leaves the house. She ignores him, gets into a taxi, and vanishes down the street. Montag obeys the chief, destroying the home piece by piece with a flamethrower. As soon as he has incinerated the house, Beatty discovers Montag's ear-piece and plans to hunt down Faber. Montag threatens Beatty with the flamethrower and (after Beatty taunts him) burns his boss alive, and knocks his coworkers unconscious. As Montag escapes the scene, the firehouse's mechanical dog attacks him, managing to inject his leg with a tranquilizer. He destroys The Hound with the flamethrower and limps away.
Montag runs through the city streets towards Faber's house. Faber urges him to make his way to the countryside and contact the exiled book-lovers who live there. He mentions he will be leaving on an early bus heading to St. Louis and that he and Montag can rendezvous there later. On Faber's television, they watch news reports of another mechanical hound being released, with news helicopters following it to create a public spectacle. Montag leaves Faber's house. After an extended manhunt, he escapes by wading into a river and floating downstream.
Montag leaves the river in the countryside, where he meets the exiled drifters, led by a man named Granger. They have each memorized books for an upcoming time when society is ready to rediscover them. While learning the philosophy of the exiles, Montag and the group watch helplessly as bombers fly overhead and attack the city with nuclear weapons, completely annihilating it. While Faber would have left on the early bus, Mildred along with everyone else in the city was surely killed. Montag and the group are injured and dirtied, but manage to survive the shock wave.
The following morning, Granger teaches Montag and the others about the legendary phoenix and its endless cycle of long life, death in flames, and rebirth. He adds that the phoenix must have some relationship to mankind, which constantly repeats its mistakes. Granger emphasizes that man has something the phoenix does not: mankind can remember the mistakes it made before destroying itself and try to not make them again. Granger then muses that a large factory of mirrors should be built, so that mankind can take a long look at itself. When the meal is over, the band goes back toward the city, to help rebuild society.