The Sun Also Rises opens with the narrator, Jake Barnes, delivering a brief biographical sketch of his friend, Robert Cohn. Jake is a veteran of World War I who now works as a journalist in Paris. Cohn is also an American expatriate, although not a war veteran. He is a rich Jewish writer who lives in Paris with his forceful and controlling girlfriend, Frances Clyne. Cohn has become restless of late, and he comes to Jake’s office one afternoon to try to convince Jake to go with him to South America. Jake refuses, and he takes pains to get rid of Cohn. That night at a dance club, Jake runs into Lady Brett Ashley, a divorced socialite and the love of Jake’s life. Brett is a free-spirited and independent woman, but she can be very selfish at times. She and Jake met in England during World War I, when Brett treated Jake for a war wound. During Jake and Brett’s conversation, it is subtly implied that Jake’s injury rendered him impotent. Although Brett loves Jake, she hints that she is unwilling to give up sex, and that for this reason she will not commit to a relationship with him.

The next morning, Jake and Cohn have lunch. Cohn is quite taken with Brett, and he gets angry when Jake tells him that Brett plans to marry Mike Campbell, a heavy-drinking Scottish war veteran. That afternoon, Brett stands Jake up. That night, however, she arrives unexpectedly at his apartment with Count Mippipopolous, a rich Greek expatriate. After sending the count out for champagne, Brett tells Jake that she is leaving for San Sebastian, in Spain, saying it will be easier on both of them to be apart.

Several weeks later, while Brett and Cohn are both traveling outside of Paris, one of Jake’s friends, a fellow American war veteran named Bill Gorton, arrives in Paris. Bill and Jake make plans to leave for Spain to do some fishing and later attend the fiesta at Pamplona. Jake makes plans to meet Cohn on the way to Pamplona. Jake runs into Brett, who has returned from San Sebastian; with her is Mike, her fiancé. They ask if they may join Jake in Spain, and he politely responds that they may. When Mike leaves for a moment, Brett reveals to Jake that she and Cohn were in San Sebastian together.

Bill and Jake take a train from Paris to Bayonne, in the south of France, where they meet Cohn. The three men travel together into Spain, to Pamplona. They plan on meeting Brett and Mike that night, but the couple does not show up. Bill and Jake decide to leave for a small town called Burguete to fish, but Cohn chooses to stay and wait for Brett. Bill and Jake travel to the Spanish countryside and check into a small, rural inn. They spend five pleasant days fishing, drinking, and playing cards. Eventually, Jake receives a letter from Mike. He writes that he and Brett will be arriving in Pamplona shortly. Jake and Bill leave on a bus that afternoon to meet the couple. After arriving in Pamplona, Jake and Bill check into a hotel owned by Montoya, a Spanish bullfighting expert who likes Jake for his earnest interest in the sport. Jake and Bill meet up with Brett, Mike, and Cohn, and the whole group goes to watch the bulls being unloaded in preparation for the bullfights during the fiesta. Mike mocks Cohn harshly for following Brett around when he is not wanted.

After a few more days of preparation, the fiesta begins. The city is consumed with dancing, drinking, and general debauchery. The highlight of the first day is the first bullfight, at which Pedro Romero, a nineteen-year-old prodigy, distinguishes himself above all the other bullfighters. Despite its violence, Brett cannot take her eyes off the bullfight, or Romero. A few days later, Jake and his friends are at the hotel dining room, and Brett notices Romero at a nearby table. She persuades Jake to introduce her to him. Mike again verbally abuses Cohn, and they almost come to blows before Jake defuses the situation. Later that night, Brett asks Jake to help her find Romero, with whom she says she has fallen in love. Jake agrees to help, and Brett and Romero spend the night together.

Jake then meets up with Mike and Bill, who are both extremely drunk. Cohn soon arrives, demanding to know where Brett is. After an exchange of insults, Cohn attacks Mike and Jake, knocking them both out. When Jake returns to the hotel, he finds Cohn lying face down on his bed and crying. Cohn begs Jake’s forgiveness, and Jake reluctantly grants it. The next day, Jake learns from Bill and Mike that the night before Cohn also beat up Romero when he discovered the bullfighter with Brett; Cohn later begged Romero to shake hands with him, but Romero refused.

At the bullfight that afternoon, Romero fights brilliantly, dazzling the crowd by killing a bull that had gored a man to death in the streets. Afterward, he cuts the bull’s ear off and gives it to Brett. After this final bullfight, Romero and Brett leave for Madrid together. Cohn has left that morning, so only Bill, Mike, and Jake remain as the fiesta draws to a close.

The next day, the three remaining men rent a car and drive out of Spain to Bayonne and then go their separate ways. Jake heads back into Spain to San Sebastian, where he plans to spend several quiet days relaxing. He receives a telegram from Brett, however, asking him to come meet her in Madrid. He complies, and boards an overnight train that same day. Jake finds Brett alone in a Madrid hotel room. She has broken with Romero, fearing that she would ruin him and his career. She announces that she now wants to return to Mike. Jake books tickets for them to leave Madrid. As they ride in a taxi through the Spanish capital, Brett laments that she and Jake could have had a wonderful time together. Jake responds, “Yes, isn’t it pretty to think so?”