Three years ago, six-year-old Tim disappeared at Lake Constance. At that time, suspicion fell on Katharina Mink, the boy's mother. Now, when the same-aged Martha goes missing, Katharina is the last person to have seen the girl alive. While the police are on the trail of a mysterious man, private detective Martin Schwarz investigates within the families. There, he uncovers unforeseen entanglements and depths, as well as a disturbing secret...