The stubborn bighead Gerhard Jäger, sentenced by the murder commission, reluctantly postpones service according to the regulations of the water protection police. Does he hate water like the plague? Until his new colleague Arda Turan, a former high-performance swimmer, brings a breath of fresh air to the WaPo team with her lively nature and direct Ruhrpottschnauze. Police chief Frank van Dijk, a real sonny boy and passionate water rat, is also on board. He spends every free minute jet skiing and flirting, but at WaPo he holds the wheel firmly in his hand. And then there is Lena Preser, the secretary of the troupe, who always gets amazing insights from the bottom of the ground with her perseverance. Under the strict eye of ambitious boss Maria Kruppka, the investigative team solves the most exciting cases and repeatedly clashes with the arrogant crime chief commissioner Carsten Heinrich from the main department.