For Nele Fehrenbach, a water police officer who has just moved from Hamburg to Lake Constance, her start in her new job couldn't have begun in a more mysterious way. The yacht, which is drifting aimlessly toward the shore, shows traces of blood. Then the yacht owner's body is found near the shore.

Lake Constance: A Haven for Money. When old Politz's boat explodes in the middle of the night on the lake, it quickly becomes clear that this cannot have been an accident. Even though Nele's colleague Andreas Rambach claims the boat was held together by nothing more than "oil and spit," evidence of his intent to smuggle soon comes to light.

It's a good thing Nele listens to her mother, Mechthild, every now and then. "A family is only as strong as its weakest link," she tells her daughter. And that turns out to be the key to solving her latest case. Because after Nele and Spitznagel discover a destroyed rail nest in the reeds in front of the Rau Guesthouse, a very strange story begins to unfold.