An “Editors’ Note” explains that what follows are the notebooks found in the papers of Antoine Roquentin, a historian who was working on a book about the Marquis de Rollebon. After traveling around Europe, Africa, and “the Far East,” he lived in the fictional town of Bouville for three years to finish his research. The Editors explain that the opening pages of the notebooks were undated but likely written earliest.
In the “Undated Pages,” Antoine writes that he intends to keep this diary in order to describe things in acute detail, tracing his experience minute by minute. Quickly he states his inability to describe a recent Saturday, when he saw children playing “Ducks and Drakes” (skipping stones) and wanted to join in. After he threw a stone into the sea, the children laughed at him, and he experienced a sort of disgust. By that night, his strange feelings have passed without a trace, and he returns to his research. The pages cut off mid-sentence.
The dated pages begin on Monday, the 29th of January, 1932. Antoine writes that something has come on him like an illness, subtly and slowly. He can’t quite tell if he himself or the outside world has changed. Soon he decides it must be he who has changed and begins writing about the moment when he decided to return to France; then, too, he was overcome with a strange disgust. The next day, his work on the Marquis de Rollebon is finished, with the exception of final revisions. Antoine is eating at the Cafe Mably, thinking about the solitude which makes up his life. It seems that his only frequent human contacts are with a man that he calls “The Self-Taught Man” and “Francoise,” the patroness of the “Railwayman’s Rendevouz,” with whom he is having sex.
Although Antoine has insisted throughout this entry that “nothing new” has happened, he reveals that he’s not been totally honest. Something new has happened: he was unexplainably unable to pick up a piece of paper. On Thursday, he overhears the hotel maid, Lucie, discussing her relationship troubles. That afternoon and the next day, he works on his history. Yet on Saturday evening, when he learns that the patroness is not at the Cafe upon arriving, Antoine has another attack of nausea. He asks Madeleine, a waitress, to play his favorite song, entitled “Some of These Days.” The song momentarily alleviates his nausea, and Antoine leaves.
He wanders the streets of Bouville, eventually running into Lucie, who is enduring verbal abuse. He ignores her, and the entry ends. On Thursday, he studies a statue outside a library and discovers that the Self-Taught Man has been working through the library alphabetically. The next day, Antoine thinks about his travels, admitting that some of what he has written about them is fictionalized. The Self-Taught Man appears to look at the pictures he took while traveling; Antoine is terse in conversation and forces him out of his room quickly, having stuffed his pockets with pictures.
The entry for Sunday describes a typical Bouville Sunday. Antoine watches with disdain as the bourgeois citizens go to church. He goes to get something to eat and reads as his listens to conversations around him. By the afternoon, he leaves to go stand near the sea. The citizens are no longer divided so rigidly along class lines; this helps Antoine find some comfort, and his writing becomes increasingly lyrical as he observes the mixed crowd. The next day, he regrets having gotten caught up in the beauty of the moment.
Later in the night, Antoine works more on his history of the Marquis, but he feels unable to get a grasp on the man as he was. He has sex with the patroness but ends the entry disgusted by her body. The next entry is written on Shrove Tuesday, also known as Fat Tuesday. Antoine receives a letter from Anny, his former lover, who states that she’ll soon be in Paris and “must” see him. Thinking about the letter, he goes to a café to eat. Once there, he encounters a man named Achille, whose awkwardness creates a number of tense scenes. Eventually, a doctor by the name of Rogé enters and called Achille “a loon.” Though this offers everyone in the café temporary comfort, Antoine soon finds himself frustrated by Achille’s willingness to accept the doctor’s assertion of his madness.
On Thursday, fog is thick in Bouville. Antoine goes to the Café Mably and discovers that M. Fasquelle, the proprietor, has not appeared. Panicked at the possibility of his death, Antoine flees to the library, where the Self-Taught Man invites him to lunch. Yet, in Antoine’s panic, he suddenly has an acute sense of the possibility of anything happening. When he returns to the Cafe, it is empty; its emptiness, even if normal, disgusts him. Saturday’s entry follows Antoine as he visits a local portrait gallery. As he looks through the portraits, he criticizes the leader’s of Bouville’s past, both for being repressive to political dissidents and for using art to manipulate their image. One, Blevigne, has even made himself seem much taller than he is.
On Monday, Antoine finds himself extremely alienated from his own writing. He becomes overwhelmed with the fact of his being submerged in the world of things, in an unexplainable wealth of existence. He cuts his hand with a knife, bleeding on the paper. Still, he feels alienated from his own words. A few days pass, and Antoine is at lunch with the Self-Taught Man. They enter a long dialogue, where Antoine is virulently critical of the Self-Taught man’s humanistic socialism. Eventually, Antoine picks up a knife in anger; the restaurant customers stare at him, and he leaves. He wanders by the sea and comes to realize the absurdity of existence as he stares at a root. Suicide, Antoine thinks, will not answer any of his questions; instead it will make him nothing more than another thing. That night, he decides to move from Bouville to Paris.
On the next Saturday, Antoine meets Anny. He notices the lack of her usual room decoration; in the past, she would decorate her rooms with shawls, masks, and other items. The two discover that they’ve had similar experiences, although Anny suggests they’ve not changed as similarly as Antoine wants to believe. Both have lost faith in the inherent privilege of events, things, or persons, but the experiences leading them up to that point are quite different. Anny is now being kept by a man. The two’s conversation is tense and dramatic, and Anny soon makes Antoine leave. She shuts the door behind him.
After this, Antoine feels a sense of freedom that seems like death. Wednesday is his last day at Bouville. That day, the Self-Taught Man has been battered by the Corsican, a guard at the library, for touching the hand of a young boy. Accused of being a “rotter” and a “fairy,” it is likely his social standing and life will be seriously hurt. Antoine defends him for long enough to let him leave the library. Antoine wanders the city. He considers how even if his self is alien to him, the consciousness in him continues on. He goes to the “Railway Rendezvous,” where Madeleine plays "Some of These Days" for him. Music, he thinks, presents something which paradoxically exists but only in a sort of beyond which is unified and harmonic. Feeling definite joy for the first time in the novel, he thinks this response might justify existence. Although he’s abandoned history, Antoine decides he will write a novel. He feels a sense of beginning. At Nausea’s end, night falls.