Fahrenheit 451 is set in an unspecified city (likely in the American Midwest) in the year 1999 (according to Ray Bradbury’s Coda), though it is written as if set in a distant future.[note 1] The earliest editions make clear that it takes place no earlier than the year 1960.[note 2]
The novel is divided into three parts: "The Hearth and the Salamander", "The Sieve and the Sand", and "Burning Bright".
"The Hearth and the Salamander"
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. Two uncaring EMTs pump Mildred's stomach, drain her poisoned blood, and fill her with new blood. After the EMTs leave to rescue another overdose victim, Montag goes outside and overhears Clarisse and her family talking about the way life is in this hedonistic, illiterate society. Montag's mind is bombarded with Clarisse's subversive thoughts and the memory of his wife's near-death. Over the next few days, Clarisse faithfully meets Montag each night as he walks home. She tells him about how her simple pleasures and interests make her an outcast among her peers and how she is forced to go to therapy for her behavior and thoughts. Montag looks forward to these meetings, and just as he begins to expect them, Clarisse goes missing. 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. Jarred by the woman's suicide, Montag returns home and hides the stolen book under his pillow. Later, Montag wakes Mildred from her sleep and asks her if she has seen or heard anything about Clarisse McClellan. She reveals that Clarisse's family moved away after Clarisse was hit by a speeding car and died four days ago. Dismayed by her failure to mention this earlier, Montag uneasily tries to fall asleep. Outside he suspects the presence of "The Mechanical Hound", an eight-legged robotic dog-like creature that resides in the firehouse and aids the firemen in hunting book hoarders.
Montag awakens ill the next morning. Mildred tries to care for her husband but finds herself more involved in the "parlor wall" entertainment in the living room – large televisions filling the walls. Montag suggests that maybe he should take a break from being a fireman after what happened last night, and Mildred panics over the thought of losing the house and her parlor wall "family". Captain Beatty, Montag's fire chief, personally visits Montag to see how he is doing. Sensing his concerns, Beatty recounts the history of how books lost their value and how the firemen were adapted for their current role: over the course of several decades, people began to embrace new media (in this case, film and television), sports, and an ever-quickening pace of life. Books were ruthlessly abridged or degraded to accommodate short attention spans while minority groups protested the controversial, outdated content they perceived in literature (yet comic books, trade papers, and sex magazines remained, as these fed into the mainstream population's desire for mindless entertainment). At the same time, advances in technology resulted in nearly all buildings being made out of fireproof materials, and the traditional role of firemen in preventing fires was no longer necessary. The government instead turned the firemen into officers of society's peace of mind: instead of putting out fires they became responsible for starting them, specifically for the purpose of burning books, which were condemned as sources of confusing and depressing thoughts that only complicated people's lives. After an awkward encounter between Millie and Montag over the book hidden under Montag's pillow, Beatty becomes suspicious and casually adds a passing threat as he leaves, telling Montag that if a fireman had a book, he would be asked to burn it within the next 24 hours. If he refused, the other firemen would come and burn his house down for him. The encounter leaves Montag shaken.
After Beatty leaves, Montag reveals to Mildred that, over the last year, he has accumulated a stash of books that he has kept hidden in the air-conditioning duct in their ceiling. In a panic, Mildred grabs a book and rushes to throw it in the 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.
"The Sieve and the Sand"
Montag and Mildred discuss the stolen books, and Mildred refuses to go along with it, questioning why she or anyone else should care about books. Montag goes on a rant about Mildred's suicide attempt, Clarisse's disappearance and death, the old woman who burned herself, and the imminent threat of war that goes ignored by the masses. He suggests that perhaps 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" that night at Mildred's house.
Montag concedes that Mildred is a lost cause and he will need help to understand the books. He remembers an old man named Faber, an English professor before books were banned, whom he once met in a park. 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. Once there, 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.
At 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 for them to reveal just how indifferent, ignorant, and callous they truly are. Enraged by their idiocy, Montag leaves momentarily and returns with a book of poetry. This confuses the women and alarms Faber, who is listening remotely. Mildred tries to dismiss Montag's actions as a tradition firemen act out once a year: they find an old book and read it as a way to make fun of how silly the past is. 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 takes more sleeping pills.
Montag hides his books in the 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. Thus 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 recklessly in the fire truck to the destination: Montag's house.
Beatty orders Montag to destroy his own house, telling him that his wife and her friends reported him after what happened the other night. Montag watches as Mildred walks out of the house, too traumatized about losing her parlor wall family to even acknowledge her husband's existence or the situation going on around her, and catches a taxi. Montag obeys the chief, destroying the home piece by piece with a flamethrower, but 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 Mechanical Hound attacks him, managing to inject his leg with a tranquilizer. He destroys the Hound with the flamethrower and limps away. Before he escapes, however, he realizes that Beatty had wanted to die a long time ago and had purposely goaded Montag as well as provided him with a weapon.
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. After wiping his scent from around the house in hopes of thwarting the Hound, Montag leaves Faber's house. He escapes the manhunt 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. Granger shows Montag the ongoing manhunt on a portable battery TV and predicts that “Montag” will be caught within the next few minutes; as predicted, an innocent man is then caught and killed.
The drifters are all former intellectuals. They have each memorized books should the day arrive that society comes to an end and is forced to rebuild itself anew, with the survivors learning to embrace the literature of the past. Granger asks Montag what he has to contribute to the group and Montag finds that he had partially memorized the Book of Ecclesiastes. While learning the philosophy of the exiles, Montag and the group watch helplessly as bombers fly overhead and annihilate the city with nuclear weapons: the imminent war has begun and ended in the same night. While Faber would have left on the early bus, everyone else (including Mildred) is immediately killed. Montag and the group are injured and dirtied, but manage to survive the shockwave.
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, but explains that man has something the phoenix does not: mankind can remember its mistakes and try never to repeat them. Granger then muses that a large factory of mirrors should be built so that people can take a long look at themselves and reflect on their lives. When the meal is over, the exiles return to the city to rebuild society.