In the neighborhood of the red lights Sonja Hausmann, a prostitute, has been stabbed to death.His corpse has been discovered by Marianne Berger,another prostitute and Günter Brock the manager of the brothel.Marianne was walking with her dog on the banks of the Main river.On the morning an old man have come to visit Sonja. Marianne and Günter listened to a quarrel.The old man wears always a beret and plays chess in a cafe.Jan finds the old man called Willi Seidel who has a blood stain on his jacket and comes with him to the office.Will affirms that he found Sonja dead and gave her a hug.When Henning and Jan want to search in Seidel's apartment they meet Herbert Krieger, a former policeman, who some hours later acknowledges that he also was a client of Sonja.
—zutterjp48