On the surface, the novel is a love story between the protagonist Jake Barnes-a man whose war wound has made him unable to have sex-and the promiscuous divorcée Lady Brett Ashley. Jake is an expatriate American journalist living in Paris, while Brett is a twice-divorced Englishwoman with bobbed hair and numerous love affairs, and embodies the new sexual freedom of the 1920s. Brett's affair with Jake's college friend Robert Cohn causes Jake to be upset and break off his friendship with Robert; her seduction of the 19-year-old matador Romero causes Jake to lose his good reputation among the Spaniards in Pamplona.

Book One is set in the café society of young American expatriates in Paris. In the opening scenes, Jake plays tennis with Robert, picks up a prostitute (Georgette), and runs into Brett and Count Mippipopolous in a nightclub. Later, Brett tells Jake she loves him, but they both know that they have no chance at a stable relationship.

In Book Two, Jake is joined by Bill Gorton, who recently arrived from New York, and Brett's fiancé Mike Campbell, who arrives from Scotland. Jake and Bill travel south and meet Robert at Bayonne for a fishing trip in the hills northeast of Pamplona. Instead of fishing, Robert stays in Pamplona to wait for the overdue Brett and Mike. Robert had an affair with Brett a few weeks earlier and still feels possessive of her despite her engagement to Mike. After Jake and Bill enjoy five days of fishing the streams near Burguete