After a charity event in a posh hotel on Lake Zurich, the evening's host is found murdered in his suite. Just a few days later, a top entrepreneur was found dead, tied to his rowing boat at the bottom of Lake Zurich. Both bodies have special features that point to a crime by Ndragetha and that put the Zurich police on high alert.

When Dominic Mercier, one of the organizers of the charity event, receives a threatening letter, the investigation turns into a race against time. When Isabel Grandjean examines the financial transactions with a mafia expert, she discovers a money laundering network that shows clear connections between the charity funds and the mafia.

Meanwhile, Tessa Ott is following a different lead. This leads via a boxing club to an orphanage, whose director is also murdered a short time later. Here, too, there are special traces on the corpse, which Tessa now knows how to interpret. Tessa is increasingly convinced that personal motives underlie the murders.