Didier Mège, a police Captain, returns to his hometown of Rouen (Normandie, France) to be closer to his ailing father who is growing more feeble each day. Didier has no time to settle down though, he is immediately called to a crime scene: a corpse has been discovered on the Abbatial square. The man has apparently fallen from the rooftop but his body is found in an unusual position; a position that Didier recalls having seen many years before. He is reminded of his childhood and a stained-glass window that his grandfather created as his "chef d'oeuvre" to achieve his degree as a craftsman. Didier will discover that the murder is linked to his family's secret past. During the Second World War Didier's grandfather and his two associates committed a horrible deed that haunts the family until this today. Now revenge is knocking on Didier's door.