In the young green of the spring forest behind the Karlsruhe Palace Garden, two female joggers discover the body of a strangled woman. Are there connections to a city map with strange markings that Chief Detective Oskar Lindt received anonymously shortly before, which indicates several deaths among wealthy elderly individuals? The investigation into a private nursing service and a dubious law firm yields vague suspicions but hardly any usable results. A humanitarian children's aid organization is also involved, yet no evidence can be found anywhere. The experienced detective falls into a deep personal crisis due to the looming failure of his efforts when a coincidence unexpectedly brings movement to the investigation.