A couple said they saw the body of a young woman taking a night bath in Schlachtensee – but Tom and Wolff cannot find any dead bodies. As the two officers go through the missing persons file, they come on the trail of the French au pair Simone. A questioning of the host family and Simone’s girlfriend confirms the suspicion that the apparently untraceable body is the missing French woman. To make matters worse, it becomes clear that Harald (Max Riemelt) and his mother of all people had an affair with Simone at the same time.