In a distant future United States, Guy Montag works as a fireman. He burns books for a government that no longer tolerates reading unproscribed texts - hence the title, as paper burns at this temperature.

451 is also the number assigned to Montag, his uniform also bearing the fiery imagery of a salamander and a pheonix. At the beginning of the novel, Montag finds great satisfaction in his work, enjoying the physical merits of burning. Kerosene, to him, smells like perfume. He loves to see things burn because he loves to see things change - an irony considering the stagnant society he inhabits. He is, perhaps, a pyromaniac, who thinks little of the repercussions of his actions.

On his return home, Montag meets with a neighbour, Clarisse McClellan, who begins to alter his worldview. Clarisse is an inquisitive and intelligent young woman, qualities very much against the status-quo of this world. We learn that society, in this time, values only instant gratification and the pleasures of speed as well as the dull entertainment of the 'parlor-wall.'She informs Montag that the current role of the 'fireman' is very different from its historical beginnings. She explains how they once protected, rather than destroyed, in the time before properties were fireproofed.

Clarisse goes on to question Montag about his life, while simultaneously telling of her own, and the subversive actions of her family - who commit such anti-social acts as conversations and taking walks.

Talking long and late, Montag is fascinated by this girl, who is quite unlike anyone he has ever met. Clarisse' innocence and insight spurs the beginnings of Montag's own intellectual awakening and, toward the end of the evening, when she asks him if he is happy, he begins to question even the most basic assumptions about himself. The revelation, for Montag, is that he is not.

At home, Montag finds his wife Mildred asleep with her 'seashell' headphones in, as usual. Before leaving her, he discovers an empty bottle of sleeping pills nearby. Realising the danger, Montag calls for an ambulance. Two disinterested technicians arrive to the scene with a snake-like machine. Performing a blood transfusion and stomach pump, they save Mildred's life. Montag is surprised to learn that they perform this service all too regularly. Mildred retains no memory of the event and even denies it happening.

Montag finds Clarisse outside, catching rain-drops upon her tongue, before her appointment with a psychiatrist. Again intrigued, Montag tries this act for himself, symbolically starting to replace fire with water.

At work, Montag is growled at by 'The Mechanical Hound', a hunting robot used to catch readers and radicals. Montage complains to his superior, Captain Beatty, about the machine, which begins to peak the Captain's attention. Beatty is presented as something of a contradiction - an intelligent man serving a regime that loathes intelligence.

The fire-crew are called to a house, where an old woman is found with many books. The books are sprayed with kerosene, but still she refuses to leave. Montag initially tries to talk her down, against the aggression of his colleagues. Beatty offers some insight about the banning of books, attempting to argue the folly of book-knowledge, though again, he proves himself to be well-read. In the end, the woman strikes a match and would rather burn than be separated from her texts. In the confusion, Montag has unconsciously pocketed a book for himself.

Returning home, Montag tries to share his confusion with his wife. Mildred is vacuous and unhelpful. Only when asked does she remember to tell Montag the terrible news about Clarisse, who has been run over and killed. This inspires a depression in Montag. When Captain Beatty comes to visit he explains more about why books are banned. A combination of political correctness and faltering attention spans was to blame for the demise of most print - only comics, trade journals and pornography was exempt. The state encourages the homogenisation of ignorance. Clarisse, he learns, had been under surveillance for her non-conformist tendancies. Beatty seems to know of Montag's dissidence, but offers him time to come back to work. Montag secretly vows never to return and begins to read the twenty (or so) books he has acquired over the years.