The novel opens as Jake Barnes, the narrator, offers an account of his friend, Robert Cohn. Jake is a journalist in Paris; a job he took on after his service in WWI. His friend also lives in Paris, although he is not a war veteran. Cohn is a rich Jewish writer, living in Paris with a controlling girlfriend named Frances Clyne. Having become restless, Cohn visits Jake’s office with the idea that Jake will join him in traveling to South America. Jake says no to this idea and is actually adamant about getting rid of Cohn.
Later that night, Jake happens to run into Lady Brett Ashley at a dance club. Ashley is the love interest for Jake. A divorced socialite, she is a free-spirited woman and tends to be rather selfish. Jake met her in England during the war while he was being treated for a war wound by Ashley. Though she does love Jake, she is ready for an intimate relationship will not fully commit to him.
The next day Jake has lunch with Cohn. Cohn is infatuated with Ashley and he is disturbed by Jake’s news that she plans to marry Mike Campbell, a hard-drinking war veteran from Scotland. Later that day Jake is stood up by Ashley, but she arrives unexpectedly later that night at Jake’s apartment with a wealthy Greek expatriate named Count Mippipolus. Once she and Jake are alone, she tells him that she is leaving for San Sebastian in Spain. She explains that things will be easier on both of them once they are apart.
Several weeks pass and we find Jake and Cohn traveling outside Paris. At the same time, one of Jake’s friends, fellow American and war veteran named Bill Gorton, arrives in Paris. Bill and Jake make plans to travel to Pamplona for the fiesta. Jake also makes plans to meet up with Cohn on his way to Pamplona. Along the way, Jake runs into Ashley who has returned from San Sebastian with Mike who is now her fiancé. They ask if they can meet up in Pomplona and Jake politely says yes. Again, in a moment while they are alone, Ashley reveals to Jake that she and Cohn had been in San Sebastian together.
Bill and Jake depart by train for Bayonne in the south of France. They meet up with Cohn and from here they head to Pamplona. They planned to meet Ashley and Mike, but the couple does not show. Bill and Jake head out for a fishing trip in a small village called Burgette while Cohn decides to stay in Pamplona and wait for Ashley.
Bill and Jake arrive in the country and spend five days fishing, drinking, and playing cards. Jake eventually receives a letter from Ashley explaining they she and Mike will soon arrive in Pamplona. Jake and Bill leave immediately to meet them. Once they arrive in Pamplona, Jake and Bill check into a hotel owned by a notable Spanish bullfighting expert named Montoya. It seems that Montoya has a fondness for Jake because Jake is especially interested in bullfighting. The entire group is finally together and they go to see the bulls being unloaded in preparation for the bullfights during the fiesta. Mike mocks Cohn for following Ashley around.
A few days later, the fiesta begins. The city is alive with celebration: drinking, dancing, and wildness. The first day is capped by a performance by Pedro Romero, a nineteen year old bullfighting prodigy, who outdoes all the other bullfighters. Ashley is entranced by the bullfights, despite the violence, and is especially amazed by Pedro Romero.
Just a few days later, while dining with friends at the hotel dining room, Ashley notices Romero at a nearby table. She convinced Jake to introduce her to him. Meanwhile, Mike verbally attacks and insults Cohn and they nearly come to blows, but Jake intervenes and calms the situation. Later that night, Ashley tells Jake that she has fallen in love with Romero and asks him to help her find him. Jake agrees to help and makes it possible for Romero and Ashley to spend the night together.
When Jake finally meets back up with Mike and Bill they are both extremely drunk. Cohn arrives and demands to know where Ashley is. A heated argument between Cohn, Jake and Mike leads to a fist fight and Cohn attacks both Jake and Mike, eventually knocking both of them out. Soon after, Jake returns to his hotel only to find Cohn lying face down and crying. Cohn is mortified by his behavior and begs Jake’s forgiveness. Jake reluctantly agrees to forgive him. The next day Jake learns from Bill and Mike that Cohn also beat up Romero when he found him with Ashley. Cohn later tries to make amends with Romero who refuses.
The next day, Romero has a brilliant day at the bullfights. He amazes the crowd and kills a bull that had gored a man to death on the streets. After his victory, he cuts off the bull’s ear and presents it to Ashley. She and Romero depart for Madrid after the bullfights. Cohn, we find out, had left earlier in the morning. Bill, Mike, and Jake remain as the fiesta comes to an end.
The following day, the remaining three drive from Pamplona to Bayonne and eventually go their separate ways. Jake makes his way to San Sebastian, further into Spain, where he plans to spend several days relaxing. However, his peace is interrupted as he receives a telegram form Ashley asking him to meet her in Madrid. He decides to go and takes and overnight train that very day.
Jake finds Ashley alone in her hotel room. She has broken things off with Romero, explaining to him that she would only destroy his career. She tells Jake that she wants to return to Mike. Jake makes arrangements for them to leave Madrid. As they take a taxi through the city, Ashley laments that she and Jake could have had such a great time together.