A homicide detective goes undercover as a patient to investigate a psychotherapist he believes is linked to a strange double murder. As his therapy sessions continue the line between fantasy and reality begins to blur....

　A dying professor of Egyptology (Boris Karloff) asks to be buried with a valuable jewel known as the Eternal Light, which he believes will grant him immortality in the afterlife. When his butler (Ernest Thesiger) steals the jewel from his tomb, Kar...