An Ancient Egyptian priest called Imhotep (Boris Karloff) is revived when an archaeological expedition finds Imhotep's mummy and one of the archaeologists, despite a warning, recklessly reads aloud an ancient life-giving spell. Imhotep escapes from the archaeologists, taking the Scroll of Thoth, and prowls Cairo seeking the reincarnation of the soul of his ancient lover, Princess Ankh-es-en-amon.