The show is based on the best-selling novel Der Nasse Fisch (The Wet Fish) by German writer Volker Kutscher, the first of his Gereon Rath novels. Set in 1920s Berlin, they follow police detective Rath, who is transferred to Berlin and tries to solve crimes in a city torn by social and political upheaval in the years leading up to Adolf Hitler's rise to power.

The story of five German friends in the years from 1941 to 1945. Their friendship was meant to last their whole lives, but the war changed everything.