When Jim Rittenshaw learns that his friend Richard Desborough is having an affair with Jim's wife Daisy, Jim kills Richard. The murdered man's ghost then takes up residence and attempts to positively influence the lives of those he had wronged.

In attempting to develop a chemical which would make a person super-intelligent, Dr. Montrose fails and the subjects of his experiments metamorphose into hideous monsters who band together and prey on humans. With the police stymied, a young detective attempts to track down the leader of the group of killers, known only to have a small crimson stain in one eye.

British Egyptologist, Professor Morlant, seeks immortality through the power of a jewel buried in the tomb of an Oriental idol. Upon his death, Morlant returns to earth to seek vengeance upon those who removed the jewel from his grave.