Thirty years after uncovering Princess Ananka’s tomb and the living mummy Kharis, along with his High Priest Andoheb, Massachusetts archaeologist Steve Banning recounts the harrowing events to his family and a gathering of evening guests, steering the tale toward the moment when the creature was believed to be destroyed. The frame shifts to Egypt, where Andoheb passes on the legend of Kharis to his devoted follower Mehemet Bey and reveals the grim plan: use tana leaves to reawaken the mummy and terminate the bloodline of the Banning expedition and its descendants. After these preparations, Andoheb expires, and Bey with Kharis heads for the United States.
Bey takes a caretaker job at Mapleton cemetery, where he begins administering the tana brew to Kharis. The monster, hungry for vengeance, resumes its pursuit of those connected to the desecration of Ananka’s tomb, with its first victim being the aging Banning. As the sheriff and coroner search for clues, Babe Hanson arrives, drawn by the disturbing deaths and fueled by his own suspicions that a mummy is stalking the town. When Jane Banning is slain, Hanson becomes convinced that an ancient evil is at work, and he recounts his theory to a newspaperman at a local bar, only to meet the same end soon after.
Dr. John Banning, son of Steve, joins forces with Professor Norman to crack the mystery of the “grayish mark” found on the victims’ throats. Norman’s tests reveal a terrifying clue: the marks are mold from a mummy, confirming Hanson’s suspicions and turning the case toward an undead culprit rather than a human killer.
Meanwhile, Bey pursues his own dangerous designs. Knowing that Steve Banning and his girlfriend, Isobel Evans, are planning to marry, Bey sets out to derail their nuptials. He has Kharis abduct Isobel and transport her to the cemetery caretaker’s hut, where Bey reveals his chilling plan: Isobel would become his bride and High Priest of Karnak, bearing him an heir to the royal line. The townspeople, growing wary of an Egyptian immigrant’s alleged involvement, converge on Bey’s location, while Kharis slips away with Isobel in the cover of night.
A confrontation erupts outside the hut when Bey is challenged, and he is fatally shot by the sheriff as the mob closes in. Meanwhile, Kharis makes a beeline for the Banning estate, with the townspeople torching the path to deny the creature an escape. Inside the house, Steve Banning fights the mummy and keeps him at bay with a burning torch, managing to rescue Isobel from Kharis’s grasp, though a blaze soon engulfs the home. The chase spills onto the balcony above, where the townspeople rain down torches and, together with the sheriff and coroner, force the mummy’s demise in the flames. The peril ends with Banning and Isobel’s swift wedding, just as Banning receives his draft notice to report for World War II duty.
