A professional was at work here. The policeman Gerd Samland was murdered in a brothel with two well-placed shots. Chief Inspector Max Ballauf (Klaus J. Behrendt) is shocked. Was his friend and colleague actually a regular at this establishment? In order to ensure that nothing is swept under the carpet within the police force, the "Internal Investigations" department intervenes: Samland, who worked for the motorway police, was involved in illegal dealings with the underworld, claims Kriminalrat Brauer. He takes over the homicide case. Schenk and Ballauf are already expecting new work. The cleaning service found a badly battered corpse at a motorway service area. The man is obviously a missing Polish long-distance truck driver.
While Schenk is already looking for clues at the trucking company, Ballauf continues to take care of the murder of his old buddy from the police academy and stands by his widow Britta. In the course of their investigation, Ballauf and Schenk come across evidence of a sensitive corruption scandal. But before they can uncover the background, they themselves are targeted by the internal investigation...