François (Valentin Vigourt) is a sickly 7-year-old boy growing up in post-WWII France. His father, Maxime (Patrick Bruel), is athletic and obsessed with sport. His mother Tania (Cécile De France), is a champion diver and swimmer. François keeps imagining he has a brother who is the exact opposite of him: handsome, athletic and forceful. At age 15, his neighbour Louise (Julie Depardieu), reveals a dark family secret: François did indeed have a brother, Simon (Orlando Nicoletti), from his father's previous marriage. He also learns that he was born Jewish but was later baptised and his name was changed. Gradually, a dark tale emerges of an extended Jewish family torn apart during the Nazi occupation of France.