Egyptian mystic Andoheb (George Zucco) is ordered by his High Priest (Eduardo Ciannelli) to stand guard over the sacred mummy of Kharis (Tom Tyler), who thousands of years earlier was entombed alive for falling in love with Egyptian Princess Ananka. Kharis can be revived or neutralized at will through the simple expedient of burning a handful of tanna leaves, a plot device that is hammered home on several occasions. Meanwhile, perennially broke archeologists Steve Banning (Dick Foran) and Babe Jenson (Wallace Ford) persuade itinerant magician Solvani the Great (Cecil Kellaway) to finance an expedition in search of Ananka's sarcophagus. Solvani's daughter Marta (Peggy Moran), suspecting that Steve and Babe are a couple of con artists, tags along with them to Egypt. Also on hand is the ubiqutious Andoheb, in his daytime guise as professor of Egyptology at the Cairo Museum. After ordering Kharis to bump off expedition members Dr. Petrie (Charles Trowbridge) and Ali (Leon Belasco), Andoheb turns his attentions to the beauteous Marta, with whom he hopes to live "in eternity" with the aid of those handy tanna leaves. But when he kidnaps Marta, Andoheb breaks his sacred trust, and thus must pay with his life at the hands of the vengeful Kharis. Much of Hans J. Salter's pulsating musical score was lifted from Son of Frankenstein.