Michelle is enjoying a peaceful retirement in a Burgundy village, close to her longtime friend Marie-Claude. When her Parisian daughter Valérie drops off her son Lucas to spend school vacation with his grandma, Michelle, stressed out by her daughter, serves her toxic mushrooms for lunch. Valérie quickly recovers, but forbids her mother from seeing her grandson anymore. Feeling lonely and guilty, Michelle falls into a depression... until Marie-Claude's son gets out of prison.

Algiers, 1938. Meursault, a quiet and unassuming employee in his early thirties, attends his mother's funeral without shedding a tear. The next day, he begins a casual affair with Marie, a work colleague. He quickly slips back into his usual routine. However, his daily life is soon about to be disrupted by his neighbor, Raymond Sintès, who draws Meursault into his shady dealings. Until one blisteringly hot day, a tragic event occurs on a beach...