Dr. Laurience (Boris Karloff) is a brilliant brain scientist who has made a startling discovery; he has learned how to transfer the thoughts and personality from one human to another. To help him with his experiments he recruits a former student, Dr. Clare Wyatt (Anna Lee), herself a brilliant scientist who shares his passion for his work, if not his ethics. Laurience is visited by a wealthy entrepreneur, Lord Haslewood (Frank Cellier), who makes him a proposition; Haslewood will fund all of the doctor's experiments, if he will agree to publish his results exclusively in Haslewood's newspapers. The promise of unlimited resources is too much for Laurience, and he agrees. However when the time comes to share his work with the London scientific community, the doctor is ridiculed, further fuelling his madness. To gain revenge Laurience constructs an evil plan which will help him achieve immortality, a plan which results in murder.