I saw this movie when I was perhaps 6 or 7 and have only seen bits of it on TV since, but I remember it all too well. A Nazi physician is trying to revive frozen high-ranking Germans, but they all come out brain-damaged. He needs a healthy brain to experiment on. A depraved assistant takes it upon himself to sic one of the brain-damaged revivees upon a houseguest, a college chum of the physician's unknowing daughter. This young lady is made out to be attractive, bright with a full head of hair.
When she wakes up her head has been chopped off and hooked up to life-support tubing. Her hair (and scalp and skull) have been replaced by a transparent dome so that her brain is visible. She can only speak in a whisper (a bit of artistic license there). The make-up on her face suggests a concentration-camp victim and her agony and helplessness are palpable. She is hectored by the physician trying to get her to send nerve impulses to some severed arms mounted on a wall.
Enough. I understand that horror movies require innocent people to suffer, but at least up until Night of the Living Dead, the suffering was largely off-screen or was kept brief. This film tortures its victim unspeakably. There is no hope for her.
The only things I can say to the movie's credit are that the atmosphere is well evoked and that it plays almost exactly like one of those old "Tales from the Crypt" EC comics from the 1950s. Of course, they were sadistic, too. Don't let a child (i.e. anyone under the age of 70) see this movie; it could damage them for life.
