A series of murders with seemingly unconnected victims puts the investigators of K11 under pressure. Three people are killed by a sniper in the Taunus area. The media soon coins the term "Taunus sniper" and fear spreads among the public. The sniper seems to be a highly strategic killer. Andreas Neff from the State Office of Criminal Investigation supports the investigators Oliver von Bodenstein, Pia Kirchhoff and Kai Ostermann. They find out that not the assassinated people but their relatives are the true victims. The investigators get drawn ever more deeply into a complex net of guilt and revenge, and step by step they uncover an enormous medical scandal.