On Sunday morning, Marie wakes the narrator to go to the beach early with Raymond. The narrator feels tired, sluggish, and tastes bitter tobacco, while Marie looks pretty in her white dress and loose hair. Before leaving their building, they encounter a group of Arabs standing silently outside a tobacco shop, and Raymond grows uneasy because one of them is his adversary from a recent dispute. They take a bus to the Algiers suburb and walk through a dusty plateau to reach a wooden cabin belonging to Raymond's friend, Masson, and his friendly Parisian wife. The group enjoys a pleasant morning swimming in the cool sea, where the narrator and Marie feel closely attuned to each other. Afterward, they share a heavy lunch of fried fish, meat, and wine, discussing plans to rent a beach house together in August.
Following lunch, Raymond, Masson, and the narrator walk along the hot beach and encounter the two Arabs again. A sudden fight erupts between the men. Masson and Raymond strike their targets, but Raymond is slashed on the arm with a knife before the Arabs manage to flee. Raymond goes to have his superficial wound treated by a doctor, while Marie and Madame Masson remain behind, visibly shaken and crying. Distressed and vengeful, Raymond later insists on returning to the beach, accompanied by the narrator and Masson. They find the two Arabs resting by a cool spring behind a rock, one of them playing a reed flute. Raymond contemplates shooting him, but the narrator persuades him to hand over his revolver instead of shooting rashly, and the men eventually walk away together.
Driven by the oppressive, blinding heat and a strong longing for shade, the narrator returns alone to the spring. He finds the Arab lying by the rock under the scorching sun. As the narrator approaches, the heat reminds him of his mother's funeral, and sweat floods his eyes. The Arab draws a knife, reflecting a blinding flash of light into the narrator eyes. Overwhelmed by the intense glare and the punishing heat, the narrator steps forward and fires the revolver once. Pausing briefly and realizing he has broken the peaceful balance of the day, he fires four more times into the motionless body, marking the definitive end of the quiet afternoon and his peaceful state of mind.