In Paris around 1902, the film opens with the narrator François Truffaut guiding us through a melodic, emotionally charged setup: Claude Roc Jean-Pierre Léaud, a young man living with his widowed mother, Madame Roc Marie Mansart. They are visited by Anne Brown Kika Markham, daughter of an old friend, who invites Claude to spend the summer on the coast of Wales with her widowed mother and sister Muriel Stacey Tendeter. The invitation promises sunshine, companionship, and the possibility of a new life, and Claude is soon drawn into a delicate web of affection, duty, and desire.
On the Welsh shore, a quiet romance blossoms between Claude and Muriel, even as Muriel’s eyesight challenges loom in the background. Their feelings deepen, and Claude persuades Muriel to consider marriage, a prospect that both of them welcome with cautious optimism. Yet Madame Roc, with Mrs Brown's quiet agreement, proposes a difficult test: they must live apart for a year, with no communication, before they can wed. This separation casts a long shadow over the young couple, foreshadowing the trials ahead and testing the strength of their bond.
Back in France, Claude reenters his artistic circles and embarks on a series of affairs, while Muriel in Wales keeps a diary that becomes a private record of longing and doubt. Encouraged by his mother, Claude writes to Muriel to break off the engagement, seeking freedom to chase his business ambitions. Muriel is left devastated by these developments, her dreams of a shared life feeling increasingly out of reach. Amid this churn, Anne leaves home to study sculpture in Paris, where she enters a provocative, non‑exclusive relationship with Claude, and later becomes entangled with Diurka, a bold publisher who whisks her away to Persia, all under Claude’s cautious encouragement. Muriel, meanwhile, sends her diary—its pages revealing a childhood lesbian episode and her own struggle with masturbation—to Claude, who publishes it against her wishes, tearing at the fragile trust between them.
Muriel travels to Paris and the two lovers briefly rekindle their relationship, finding a momentary warmth in each other’s company. But the truth about Claude’s entanglement with Anne surfaces, and Muriel, overwhelmed by the revelation, plunges into a deep depression and returns to Wales. Anne, meanwhile, becomes engaged to a Frenchman named Nicholas but falls ill and dies among her family, with Diurka at her side. The sorrow that follows ripples outward, shaping the choices of everyone involved.
Diurka then reveals to Claude that Muriel plans to leave home for Belgium. Claude meets her as she boards a ship at Calais, and they share one last night in a hotel, during which Muriel also loses her virginity. In the morning, she declares that they must part forever, trusting that Claude is not suited for marriage, despite his renewed proposal. A subsequent letter promises a pregnancy, raising Claude’s hopes, but a second letter clarifies that the risk was unfounded and their romance is truly finished. He later learns that Muriel has married and become a schoolteacher with a daughter. The whole saga inspires Claude to write a novel—an attempt to capture the turbulent, intertwined fates of the sisters—with Diurka serving as the publisher.
In the 1920s epilogue, the narrator notes that Claude has become a successful, though still unmarried, author. His mother is gone, and yet he remains haunted by what might have been—the artistic gifts of Anne, and the children that Claude and Muriel might have had. The film closes on a contemplative note, showing how memory and creativity can coexist with loss, and how the past lingers in the life of a man who turned his personal history into art.
