In a small midwestern town a scientist creates a pill that can revert human behavior to its most primal. He dies-but not before he gives the deadly prescription to the town's doctor, who accidently mistakes it later on for his migraine medication. He very quickly becomes addicted to it, feeding on the local populace. It turns him in to this caveman-looking creature who feeds on blood. A side effect of his feeding is that he transmits a strange blood disease to his victims, who soon die. This flick really reminded me of THE NEANDERTHAL MAN, which in turn is your usual Jeckyll & Hyde story.