When an inspection of the mummy by Whemple's friend Dr. Muller () reveals that the viscera were not removed, Muller deduces that although Imhotep had been wrapped like a traditional mummy, he had been buried alive.
Also buried with Imhotep is a casket with a on it. Despite Muller's warning, Sir Joseph's assistant Ralph Norton () opens it. He reads aloud an ancient life-giving, the 'Scroll of '. Imhotep rises, the sight of which snaps Norton’s mind and causes him to laugh hysterically, as the Mummy shuffles off with the.
Ten years later, Imhotep is masquerading as a modern Egyptian named Ardath Bey. He calls upon Sir Joseph's son Frank () and Professor Pearson () and shows them where to dig to find the tomb of the princess Ankh-es-en-amon. After locating the tomb, the archaeologists present its treasures to the and thank Bey for making their discovery possible. It is further revealed that Imhotep's horrific death was punishment for: attempting to resurrect his forbidden lover, Princess Ankh-es-en-amon.
Imhotep soon encounters Helen Grosvenor (), a half-Egyptian woman bearing a striking resemblance to the princess. Believing her to be Ankh-es-en-amon's, he attempts to kill her, with the intention of mummifying her, resurrecting her, and finally making her his bride. Helen is rescued when she remembers her ancestral past life and prays to the goddess Isis to come to her aid.
The statue of Isis raises its arm and emits a flash that sets the Scroll of Thoth on fire. This breaks the spell that had given Imhotep his immortality, causing him to crumble to dust. At the urging of Dr. Muller, Frank calls Helen back to the world of the living while the Scroll of Thoth continues to burn. Boris Karloff in a shot used about four times in the movie In credits order • as Ardath Bey / / The Mummy • as Helen Grosvenor / Princess Ankh-es-en-Amon • as Frank Whemple • as Sir Joseph Whemple • as Dr. Muller • as Ralph Norton • as The Nubian • Kathryn Byron as Frau Muller • as Professor Pearson • James Crane as Pharaoh Amenophis • as The Saxon Warrior. (Henry Victor is listed in the credits but never appears in the film.