At first, it seems to be just another sad case:

No one realizes that 84-year-old Theo Reifennrat, who had been living isolated for the past twenty years, died in his home several days ago. However, during the investigation, Pia Zander and Oliver von Bodenstein discover the remains of many women on the deceased's property. Was Reifennrat a ruthless serial killer who buried his victims under the dog's kennel? Together with his wife Rita, he had been a foster parent to orphans and abandoned children for many years, providing them with a loving home environment.

As Pia and Oliver stumble upon dark chapters of the Reiffenrath family's history, another woman disappears. All the women have vanished close to Mother's Day. Pia is convinced: The killer is still out there, searching for his next victim. And Mother's Day is approaching.