The "Hinterkaifeck Murders" are one of Germany's most infamous crimes and one of its most puzzling cold cases. In the winter of 1922, the Gruber family's nerves were shattered by signs that someone had been watching them. Footsteps in the snow. Strange noises in the attic. A broken lock on a barn door. On March 31st, 1922, all six are found viciously slaughtered with an ax and a hunt begins for a maddeningly elusive murderer.