一名科学家创造了一副机器，可以透视第四空间的所有猛鬼幽灵，但他始料不及的、却是这副机同时使这一双双的猛鬼变成饿鬼，最后连自己也产生变化，变成一个「活魔人」。Dr. Pretorius and his colleagues are working on a sensational experiment: by means of stimulation of the pineal gland, they want to open the human mind to higher dimensions. When the experiment succeeds, however, they are immediately attacked by terrible life forms, which apparently are floating around us all the time. When Dr. Pretorius is killed by one of them, Dr. Tillinghast is under suspect and thrown into the psycho ward due to his stories. Only the ambitious psychologist Dr. McMichaels believes him and wants to continue the experiment.