The Mafia on idyllic Lake Constance? Together with her Swiss colleague, Captain Aubry, Nele is working around the clock to investigate organized crime after two water police officers were murdered. An initial lead points to Pucci, an Italian shoe dealer who is believed to be a member of the Calabrian Mafia.

Lake Constance is considered Europe's largest ship graveyard. As a result, it attracts treasure hunters from all over the world. And that's exactly the kind of treasure hunter the WaPo spots on its patrol. Diver Arno Gierke admits that he misses both his partner and his boat.

The body of a young, athletic man is floating lifelessly in the lake. When Nele and Paul pull the surfer—who is already severely hypothermic—from the water, it's too late to save him. Daniel Dellbrück was the victim of deliberate blows—with a paddle?