Contractor Detlef Börner is killed in an unusual way at night in the construction container of his large construction site: he is first incapacitated by the shovel of a wheel loader and then left to his fate with a blood-thinning injection. Shortly thereafter, a second murder occurs in Marbach. Restaurant operator Sigrun Karrenbrock is run over by a stolen off-road vehicle and also bleeds to death. A photo and the method of murder lead the detectives to the fact that the two cases are connected. They actually discover that Börner and Karrenbrock used to be a couple. The last call Börner answered came from Michael Joswig, a former fellow student. He appears to be the sole survivor of a circle of friends that broke up many years ago.
The Stuttgart detectives Lannert and Bootz believe that the motive for the murders can be found in this circle of friends, but Joswig says nothing about it. The deeper Lannert and Bootz delve into the lives of the murder victims, the more convinced they are that the killer wanted to punish his victims. However, this also puts Joswig and his family in mortal danger.