Dr. James Xavier (Ray Milland) is a brilliant but unorthodox researcher whose work with human sight has yielded an experimental chemical that may vastly increase the range of what we can see. Despite the misgivings and warnings of the two people closest to him, Dr. Diane Fairfax (Diana Van Der Vlis) and Dr. Sam Brant (Harold J. Stone), he uses it on himself and finds that he is able to look inside the human body in real-time. This gives him the ability to save the life of a patient in surgery, but in the process, he offends a top physician and calls his own judgement into question. He won't stop or even slow his experiments, however, and when Sam is accidentally killed trying to stop him, he is forced to flee.