Summary The sudden end of a fun boat trip with friends: When a guest falls over the railing and sinks into Lake Constance before Mechthild's eyes, it is a case for her daughter Nele and the WaPo team. It quickly turns out that the dead man had consumed a poisonous cocktail with the liqueur "Konstanzer Kwitte". The married couple Elke and Bernhard Schröder, who distill the new liquor, cannot explain how the poison got into their hand-filled bottles. But then many pieces of the puzzle come together: Boat owner Clemens Vollmer, who can no longer pay for his berth, was once Elke Schröder's lover and an employee in the distillery. The Schröders' house has long belonged to the beautiful real estate agent Anna Devroius. And then time is running out. More poison victims have to be treated in hospitals. Mechthild unknowingly gives a friend a contaminated bottle of "Konstanzer Kwitte" for his birthday and blames herself endlessly. The police seem powerless. All suspects have an alibi. But then Jakob Frings comes up with a ruse and Nele appeals to wounded male pride. Nevertheless, everything would have gone up in smoke in the end if Paul had not been able to dive silently. The main question on his mind is: is Julia actually having an affair with her colleague Jakob?

• Crime