Klaus Kinski stars as Dr. Karl Gunther, a brilliant but psychopathic doctor who was the son of a demented Nazi SS surgeon. He rents out apartments, hides in the ventilation shafts and tortures his tenants with rats and other devices. However, a beautiful young girl moves in that he begins to obsess over and a man shows up claiming that he was responsible for his brother’s death and seeks revenge. Gunther has a lot on his plate now. This sadomasochistic film is a dark and twisted look into the mind of a helpless sociopathic serial killer. Kinski plays the role like a fine-tuned fiddle and nails his mannerisms. It’s a great film that differs from usual slashers but see it for Kinski if not for the rest.