Arda Turan, former high-performance swimmer, has just started her service at the Duisburg Water Protection Police, where there is already the first corpse. Stefan Buhl is dead at the edge of the harbor. What Carsten Heinrich von der Kripo quickly identifies as a fatal occupational accident raises doubts among Gerhard Jäger, who was sentenced to the "WaPo" by the murder commission. A look at the corpse tells him it was murder. But leave the investigation to the Kripo? - No chance!