Summary Paul takes part in an open water swim. In the middle of the lake, a swimmer next to him gets into trouble and dies. The dead man is the businessman Max Behringer, who has made many enemies with a wind farm project on the Swiss Seerücken. The island of Reichenau directly opposite is therefore in danger of losing its status as a UNESCO World Heritage Site, with corresponding consequences for tourism. Nele and Julia ask around on Reichenau and become aware of Behringer's sister Tina Leiner. She runs a hotel and would be particularly affected by the indirect effects of the wind farm. But Behringer's business partner Urs Thaler and his partner Jan Hermann also have their reasons for murder. Paul and Jakob are investigating Behringer's Swiss environment. They are assisted by the brittle Swiss colleague Ladina Brugger, who has her own qualities. Julia and Jakob, on the other hand, show few qualities. After Nele discovers their relationship and gives them an ultimatum, the lightness no longer really sets in. Julia believes that she will make Jakob unhappy, and after a conversation with Mechthild, he makes a momentous decision. Mechthild tells her lodger Jakob that she has only ever regretted the things in life that she did not do.

• Crime