On the excursion steamer "Main Perle" the members of a bowling club are celebrating a party.Robert Geller, a solo entertainer is singing.The passengers are drinking and dancing.The waiter Dirk Kaufmann has been beaten and stabbed in a storage room, but he managed to reach the dancing room where he dies.Lea and Jan know the boat captain Erich Grabowski who has drunken too much and they send him for a medical examination.In the storage room the police finds a knife and some condoms.Lea and Jan know also Sonja Kaufmann, the widow , who works also as waitress on this boat and who is not able to say when she did see her husband for the last time.All the passengers and the members of the crew are sent to the police station.Then Lea speaks with Robert Geller about Sonja Kaufmann, a woman who was teacher in Ukraine and now working as waitress on this boat. —zutterjp48