S1, E4: The 92-year-old Holocaust survivor David Joshua Goldberg has been executed in his own home in Taunus. The murderer wrote the number "16145" on the hall mirror using his victim's blood. During the autopsy of the body, forensic pathologist Henning Kirchhoff makes a strange discovery: on the inside of the upper left arm, they find the remains of a tattoo like those that were common in the Waffen-SS. Two more murders are committed following the same pattern. Why would someone kill three old people? And what does the mysterious number mean?