The scene of the action is rather unusual: the extensive network of sewers under the city of Berlin. This cesspool underworld, whose canals led from the east to the west part of the city and vice versa, had made a gang of criminals the main trading point for their hot goods. It's a dirty business, but anyone who dared to disrupt or stop it had to expect to disappear into the sewer network forever. But Kriminalrat Steffens and his colleague Rödel are on the trail of the cold-blooded criminals and do everything in their power to stop them and put them behind bars.