The Leopard Hunts in the Dark

It will not occur to any sensible person to want to wash away ink stains with ink, oil stains with oil. Only blood should always be washed away with blood. Bertha von Suttner
Martin Kuhlmann finds an Advent calendar on his desk in the morning. He puts it to one side, thinking it's a silly joke because he doesn't like chocolate. A new murder case distracts him. The shipowner asks the first chief inspector of the Hamburg LKA to investigate. His only daughter has just been found dead by him.
He hands the Advent calendar back to his colleagues. A few seconds later, the colleagues are standing pale in his office: behind doors one to four there is no sweet surprise, as expected, but a photo of a woman. The fourth is the picture of the murdered shipowner's daughter from Blankenese. They hurriedly remove the cardboard. Horrified, they stare at the faceless heads of female persons, as can be seen from the hair. Now a race against time begins for the team.