Chief inspectors Max Ballauf and Freddy Schenk are called to a canal on the outskirts of town. A 19-year-old drug addict has been murdered. It quickly turns out that the victim, Lara Krohn, went on the street for her addiction. Her best friend, Kim, who is the same age, suspects that Lara was murdered by a customer. coroner dr. Roth is able to secure several traces of foreign DNA on the corpse. Due to the many in questionperpetrators, the inspectors are heavily dependent on the laboratory evaluation of these traces. But in this situation, of all things, in which they urgently need the help of their colleague Natalie Förster from forensic technology, she is not really focused. Why does Natalie suddenly seem so agitated and seems to be deliberately delaying investigation results? And why does she suddenly start looking for the culprit on her own?