An expedition sets off for the last land of Mu, where legend has it that a killer death ray is emitted from the eye of a golden idol.
The Black Magic cult of Ubasti, based on the isle of Lemuria, believes that Nadji, a princess of Egypt, is a reincarnation of their long-dead goddess, Ossana, and intend to sacrifice Nadji so that Ossana may be resurrected. Nadji has taken refuge at the California home of Frank Chandler, an American raised in the east and possessed of White Magical powers, who calls himself "Chandu". Vindhyan, high priest of the cult's California outpost, learns of this and ultimately succeeds in placing her in a trance which Chandu cannot easily break, propelling him to move her to safety, choosing the port of Suva in the South Seas. There, aided by his sister Dorothy, nephew Bob and niece Betty, Chandu is able to revive her and deal with Vindhyan, only to have the evil Voice of Ubasti, highest of the high priests, spirit her to Lemuria through the magic Circle of Ola. Chandu, Dorothy, Bob and Betty set out in pursuit but end up shipwrecked on Lemuria itself, with his family also now held for sacrifice while Chandu is plunged into the endless maze of caverns beneath the evil Temple of Ubasti, shrouded from his own powers by the full forces of Black Magic.
To protect a magic talisman from being used for evil, a teenage boy named Billy Batson is given the power to become an adult superhero, Captain Marvel, with a single magic word: "Shazam!"
Produced at the same time as the more well-known The Twilight Zone (1959), this series was an extension of the tradition of radio horror and supernatural dramas such as Light's Out, The Mysterious Traveler and The Witches Tale. As with the Twilight Zone and the radio programs each tale was book-ended by an introduction and conclusion by a host. However, rather than creating fictional stories with supernatural twists and turns, this program sought out "real" stories of the supernatural, including ghosts, disappearances, monsters and the like, re-creating them for each episode. No solutions to these mysteries were ever found, and viewers could only scratch their heads and wonder, "what if it's real?"