Following the death of his sister, who was co-director with him of the Cowan Research Center in Pasadena, Dr. Frederick Munson was ousted and replaced by his widowed brother-in-law, Dr. Edmund Redding. Through Redding's son, Timmy, Munson has been able to learn of a secret project at the institute involving the use of hypnosis to regress subjects to past lives, which information Munson passes along to a friend, Dr. John Janney. To a newspaper editor-friend, Munson relates what happened next: through the hypnotic regression, Redding established that Ann Taylor was a reincarnated Aztec woman and, via her recovered memories, was able to find hidden chambers in the Great Pyramid of Yucatan, which store a treasure of the ancient Aztecs. However, the treasure was guarded by a living mummy, which killed Redding but was captured and brought back to Pasadena by Redding's assistants. As Munson conspired to regain control of the Cowan Institute, Janney plotted to steal the mummy and learn its secrets. A hired thief locates the mummy, but it escapes him, and makes for the home of Ann Taylor...