A Secret follows the life of a Jewish family in post-World War II Paris. François, the son of Maxime and Tania, is a solitary and imaginative child who invents for himself a brother and the story of his parents’ past. One day, he discovers a dark family secret that shatters his life forever: before the war and well before François’s birth, his father Maxime was married to Hannah with whom he had a son. At a wedding Maxime met Tania, a young, athletic and beautiful swimmer. He felt madly in love but decided to remain faithful to Hannah. When the Nazis invaded France, their Jewish families and friends were deeply divided on what action to take and how they should live their religion and cultural heritage as Jews. Maxime decided to move his family to the free zone and left ahead of them. On her way with her son to meet Maxime, Hannah made a decision that would change her life and that of her family forever, leaving both Maxime and Tania to make difficult choices to survive the war. With the birth of François, the pair started a new family in post-war France, hoping that the existence of Hannah and her son would remain a secret. When François discovers the truth, the family will be forced to revisit their difficult past.