Thirty-nine-year-old Romane is a doctor and hypochondriac. Yet, her usually uneventful life changes when one of her patients insists that she saw her coming out of a hospital in Marseille, looking very ill. But Romane is perfectly healthy and has never stepped foot in Marseille. So who did her patient see? Romane sets off for the south of France, determined to uncover the mystery of her lookalike. Her investigation leads her to Juliette, a bookseller in Avignon. When the two women meet it soon becomes clear they are twins. But how is it possible that neither of them knew of each other's existence? What secrets have their families been keeping? On their search for the truth the two sisters embark on an astonishing journey filled with both pain and joy.