Inspector Lucas is appalled. The body of 60-year-old Maria Bolte is found in Regensburg, on the banks of the Danube. There are increasing indications that Maria Bolte pursued old-age prostitution out of social hardship. Ellen Lucas picks up the trail that leads her to Club Mitzi. According to club boss Hermann Liebl (45), a well-known figure in the city, there are problems in the milieu. Older women who prostitute themselves for little money are increasingly disrupting business. Suddenly Philip Schumann (32) is standing in the door, who flees at the sight of the investigative team. Philip becomes the prime suspect when it is revealed that he was in close contact with the older prostitutes. The evidence against him is concentrated in the "Tree House", a pub with a boarding house run by Philip's mother Nadja Schumann (50).to be led.
Desperate widower Ferdinand Bolte (65) threatens to run amok when he learns of his wife's double life. Meanwhile, Nadja turns out to be a former noble Munich prostitute who, out of pity, makes rooms available to the local old ladies. Among them is Agneta Wilhelm (59), a former school friend of Ellen's landlord Max. Liebl has a hard time speaking to Nadja and Agneta, while Philip continues to keep a low profile. What was his relationship to the dead woman and what connected him to the pimp Liebl? What did widower Bolte really know and what is he planning? Detective Lucas knows that she won't solve the case until she can break through Nadja and Agneta's silence. The situation escalates when the pimp Liebl is found stabbed in the backyard of his club.