The narrator, Jake Barnes, describes Robert Cohn, a rich Jew who graduated from Princeton with low self-esteem, had an unsuccessful marriage, lost most of his inheritance, and moved to Paris with an exploitative woman, Frances, to write a novel. Jake plays tennis with him. Cohn sold his novel in America and returned with arrogance and a craving for adventure. He frequently imposes on Jake.
One night, Jake picks up a girl, Georgette, and turns down her sexual advances, explaining he is "sick." They end up at a dancing-club, where Jake sees the beautiful and independent Lady Ashley, known to him as Brett. He eventually leaves with her; they have had a romantic relationship in the past, and though they kiss, Brett does not want to go through "'that hell again.'" They briefly discuss Jake's physical condition, which appears to be impotence. They meet one of Brett's friends, Count Mippipopolous. Jake makes plans to see her tomorrow. In his bed, he cries when thinking about Brett, and is woken when Brett drunkenly comes up. She invites him to go out with her and the count for dinner tomorrow, kisses him, and leaves.
The next day, Cohn asks Jake about Brett; he explains she's getting a divorce now and is going to marry Mike Campbell, who is currently in Scotland. Cohn admits he's falling in love with her. Jake says he met her while he was in a hospital during the war; she was a volunteer nurse and had married the man whose name she took, Ashley. Later, after Brett blows off a date with Jake, Frances humiliates Cohn in front of Jake. Jake leaves, unable to stand it.
Brett shows up with the count. Brett joins Jake in his room, and Jake says he loves her. Brett sends the count out for champagne. Jake asks Brett if they could live together, but she says they couldn't, as she would "tromper" (be unfaithful to, or elude) him. She says she is going away from him tomorrow, to San Sebastian, until Mike comes back. The count returns and shows his scars on his stomach and back from arrow wounds in various wars. They go to a club. Brett tells Jake about Mike, then tells Jake she is "'so miserable.'" They take the count's car to her hotel, but Brett doesn't want Jake to come up with her. They kiss at her door, but Brett pushes him away before leaving.
Jake does not see Brett until she returns from San Sebastian, nor does he see Cohn, who takes a trip to the country. He works hard in preparation for his trip at the end of June to Spain with Bill Gorton. Bill arrives in Paris, and they run into Brett, just back from her trip. That night, they meet up with Brett and Mike. Brett introduces Mike as an "'undischarged bankrupt'"; he explains that his ex-partner "'did me in.'" Mike is very drunk and possessive of Brett.
Jake receives a letter from the vacationing Cohn, who is eager to go on the fishing trip with Jake and Bill. Jake writes him and gives him instructions for where to meet them in Spain. Mike also asks if Jake would mind if they accompanied him to Spain, and Jake says it's fine. When Mike leaves, Brett tells Jake that it might be "'rough'" on Cohn to accompany them, as she went to San Sebastian with him. Bill and Jake take a train to Bayonne and meet Cohn that night.
Jake, Bill, and Cohn hire a car and drive to Pamplona. They discuss Brett and Mike; Cohn bets Bill that they won't arrive. At night, Jake and Cohn go to meet Brett and Mike's train; they are not on it. Cohn tells Bill not to worry about the bet. Jake receives a telegram from Brett and Mike; they've stopped over in San Sebastian. They make plans to leave tomorrow; if Brett and Mike get in later, they can follow them. The next day, Cohn says he won't be leaving with them. He explains that he is supposed to meet Brett and Mike in San Sebastian, as he had suggested it to Brett. Bill and Jake share information about Cohn and Brett, and decide they're better off without him and take a bus to Burguete for fishing.
Bill and Jake bond while fishing, and meet an Englishman named Harris at their inn. One day, Jake receives a letter from Mike; Brett passed out on the train, so they decided to recuperate in San Sebastian with old friends. He says they are going to Pamplona. Jake and Bill take a bus to Pamplona. They talk to the head of the hotel, Montoya, and learn about the bull-fights for the next couple of days. Montoya believes he and Jake are true, passionate "aficionados" of bull-fighting. The good bull-fighters stay at Montoya's hotel. Jake describes the "unloadings" of the bull-fights to Bill: they release the bulls from their corrals, and they chase and gore steers, young oxen castrated before sexual maturity. The purpose is to calm down the bulls and prevent them from fighting each other. Jake and Bill find Brett, Mike, and Cohn, and they watch the bulls unloaded. One steer is gored and excluded, while the other befriends the bulls. Brett is fascinated. Later, Mike says Cohn follows Brett around like a steer and that he is not wanted. Bill leads Cohn away. While Mike knows Brett has affairs -- she tells him -- he finds Cohn pathetic. Later, everyone has a pleasant dinner together, pretending nothing happened. Jake has a rough night, tormenting himself with thoughts of Brett. Pamplona gets ready the next two days for the fiesta.
The fiesta explodes at noontime on Sunday. While some people are at mass, as San Fermin is also a religious festival, music, dancing, and drinking fill the streets.
Wearing wreaths of garlic, dancers chant around Brett in a circle. They do the same to Bill and Jake. Afterwards, they seat Brett on a cask from which they draw wine, and give her a wreath of garlic. Jake, Bill, and Mike share food and drink with the Spaniards. Jake wakes the next morning to the rocket announcing the release of the bulls. He watches from the balcony. Men run down the street to the bull-ring, chased by bulls.
Jake and his friends go to the bull-fight that afternoon. Jake gives some advice to Brett about watching the fight; she is nervous about what will happen when the bull attacks the horse. Jake returns to the hotel for his wine-skin, where Montoya briefly introduces him to Pedro Romero, an extremely good-looking young bull-fighter. Jack finds the fight good, as Romero is a "real" bull-fighter. Later, Mike points out and Brett admits that she could not stop staring at Romero. Romero dominates the second day of fighting. Jake explains to Brett why Romero is so skilled a matador. Mike jokes that Brett is falling in love with Romero.
At dinner in the hotel, Romero invites Jake to his table. They discuss bull-fighting. Jake introduces him to his friends, and Brett flirts with Romero; Mike, drunk and disorderly, makes disparaging comments to Romero and, when he leaves, to Cohn. Later, Brett tells Cohn to leave her and Jake alone. She admits she has fallen in love with Romero and cannot help it. She feels she has to do something, as she has lost her self-respect with the way Mike and Cohn are around her. She asks Jake to help her through this, and they find Romero in the café with other bull-fighters. Romero joins them. Jake leaves with an excuse, but he makes it clear it is to leave Romero and Brett alone. When he returns later, they are gone.
Jake reunites with Mike, Bill, and Cohn. Mike says that Brett has gone off with Romero. Cohn asks Jake if it's true, and when he receives no answer, calls Jake a "'pimp.'" They fight, and Cohn beats up Jake and Mike. Later, at the hotel, Bill tells Jake that Cohn wants to see him. Jake reluctantly goes to Cohn's room. Cohn is crying and begs Jake's forgiveness, and says he'll be leaving in the morning. He says he can't take the way Brett treats him like a stranger, after they had lived together in San Sebastian. Jake says goodbye to him.
Jakes wakes and goes to the bull-ring to watch the bulls run in. A bull gores one man in the back. Jake reads about the man in the paper the next day, and the town has a funeral for him the day after that. Jake describes how Romero killed the bull the afternoon of the funeral. Its ear was cut off and given to Romero, who gave it to Brett. She discarded the ear in her hotel room's drawer. Bill and Mike tell Jake that after Cohn beat up him and Mike, he found Brett in Romero's room and beat up Romero badly. When he tried to apologize to Romero, the bull-fighter hit Cohn in the face, and then threatened to kill him if he weren't out of town by the morning. Brett told Cohn off until he cried. Brett is now taking care of Romero. Mike also relates Brett's unhappy relationship with the Englishman Lord Ashley (from whom she received her title).
It is the last day of the fiesta. Brett tells Jake and Bill at the café that Romero is badly hurt and won't leave his room, though he is still going to fight. Mike angrily tips over the table. Brett leaves with Jake. She tells him she is happy, and asks him to go to the fight with her. After lunch, Jake, Bill, and Brett sit ring-side at the fight. Three matadors are there -- Romero, Marcial, and Belmonte. Belmonte, a legend who recently came out retirement, renowned for working close to the bull and gravely endangering himself, goes first and is very good, but not as good as he used to be, and the crowd turns against him. Romero is elegant in the "quite," in which the bull charges all three matadors. With his own bull, whose vision is impaired, Romero works to make the match exciting, but the crowd does not understand the situation, and believes he is afraid. He brilliantly handles the last bull, the one that gored the man the other day. His brother cuts the ear off the bull and hands it to Romero, who gives it to Brett. That night, Mike tells Jake that Brett left with Romero on the train.
The fiesta is over the next morning. The men split up, and Jake ends up in San Sebastian. He spends several relaxing days there until he receives a telegram from Brett in Madrid, saying she is in trouble and asking him to come to her hotel. He arrives in Madrid on the overnight train. Brett is happy to see him and kisses him, and says she made Romero leave yesterday. He wanted to marry her so that she "'couldn't go away from him.'" Ultimately, she feels she could have lived with him had she not seen it would be bad for him. Brett cries, and Jake holds her. She says she is returning to Mike. They get train tickets for that night, and later go for a taxi ride through Madrid. Brett laments that she and Jake could have had "'such a damned good time together.'" Jake replies, "'YesIsn't it pretty to think so?'"
