While working as a sea rescuer, Katharina Venner finds a young woman, Annika Bohn, murdered at sea. Katharina is shocked: her husband Nils is arrested as the main suspect. Nils was on the beach with Annika on the night of death and was so drunk that he cannot remember. But murder? Unthinkable! Katharina knows the dead woman, she was a guest in her parents' hotel. Since the police only seem to be investigating Nils, they start investigating.