In the stillness of his Paris apartment, Jean Daragane has built a life of total solitude. Then a surprising phone call shatters the silence of an unusually hot September, and the threatening voice on the other end of the line leaves Daragane wary but irresistibly curious. Almost at once, he finds himself entangled with a shady gambler and a beautiful, fragile young woman, who draw him into the mystery of a decades-old murder. The investigation will force Daragane to confront the memory of a trauma he had all but buried.