Miriam Franz (Martina Gedeck) has just turned forty and is starting a seaside vacation with her husband André (Peter Davor) and fifteen-year-old son Nils (Lucas Kotaranin) on the Schlei, a narrow inlet of the Baltic Sea in Schleswig-Holstein in northern Germany. André has given Niels permission to bring his twelve-year-old girlfriend Livia (Svea Lohde) along for the trip. Miriam is concerned they may take their relationship to a physical level, but André seems unconcerned.