The investigation into the murder of a pediatric surgeon requires a great deal of sensitivity from Flückiger and his new police colleague Liz Ritschard. Because the closer the inspectors get to the truth, the more tragic is the family drama that unfolds before them: Sunday afternoon in Lucerne. At the solidarity run for a children's charity, Dr. Lanther (Benedict Freitag), the medical director of the Pilatus Clinic, and his deputy Marco Salimbeni (Thomas Sarbacher). In the middle of the run, Lanther is murdered. A scalpel is stuck in his throat. Urine samples from the forest floor prove that Salimbeni and Lanther briefly paused the run and relieved themselves just meters apart.
Inspector Reto Flückiger (Stefan Gubser) and his team focus their investigations on the private environment of prominent pediatric surgeon Lanther. His wife Imelda (Regula Grauwiller) had an affair with Salimbeni, which Lanther had obviously discovered and which led to a rift between the two doctors. But then the tragedy in the family of a police officer scratches the image of the infallible doctor. Suddenly, Lanther's little patients and their parents play a role in this murder case.