As he steps out of a Berlin club and onto the banks of the Spree at dawn, he sees the body of a woman floating among the branches. Instead of going to the police, Hubert Canitz keeps the discovery to himself. But the sight haunts him - and it conjures up the memory of a death mask that hung in his parents' hallway during his childhood: the Unknown from the Seine. When he asks his mother about it, a frantic spot the size of an apricot forms on her face, and she nervously avoids his gaze. Driven by curiosity, he begins to research water corpses in literature, art, and history, until something dawns on him. Wasn't his mother's sister drowned while fleeing from West Prussia in the Frisches Haff during the cold months of 1945? Could this be the reason for his mother's strange behavior and her persistent silence? A dramatic turn of events unfolds.