The Southern Engineering Company is trying to drain a swamp, but the workers fear that the area is haunted by the Mummy and his bride. The Scrips Museum sends Doctor James Halsey (Dennis Moore) and Doctor Ilzor Zandaab (Peter Coe) to confer with the head of the reclamation project, Pat Walsh (Addison Richards). They are there to search for the mummies buried in the swamp. As they speak, news comes through that a worker has been murdered there.
That evening, Doctor Zandaab sneaks into the swamp and meets with Ragheb (Martin Kosleck), a disciple of the Arkam Sect, of which Doctor Zandaab is a high priest. The monster has been moved to a deserted monastery. As he brews the sacred tana leaves, Zandaab explains the legend of Kharis and Ananka. The sacristan of the monastery wanders into the ritual and is killed by Kharis (Lon Chaney Jr.) as he rises.
The mummy of Ananka (Virginia Christine) rises from the swamp after a bulldozer uncovers her. She is covered with mud, but it is washed away, revealing her beauty. Cajun Joe (Kurt Katch) finds her wandering in the swamp calling for Kharis. He takes her to the local pub owner, Tante Berthe (Ann Codee) for help. Kharis finds her there and kills Berthe, and Ananka runs away. Ananka is found unconscious by the road by Halsey and Betty Walsh (Kay Harding), Pat Walsh’s niece, and they take care of her. She has no memory, but an incredible knowledge of ancient Egypt. Kharis appears again and Doctor Cooper (Holmes Herbert), Ananka’s doctor, is killed. She runs again and Halsey and the others go after her.
The monster kills Cajun Joe and Ananka runs to Betty’s tent, with Kharis after her. He steals her away. Betty asks Ragheb for help finding Doctor Halsey, but he takes her to the monastery instead. Zandaab, already giving the tana-leaf serum to Ananka, is angry about Ragheb’s advances on Betty. He orders him to kill her, but Ragheb kills Zandaab instead. Ragheb can do nothing as Kharis brings down the walls of the Monastery on them all. Betty and the others find the mummified remains of Ananka.
The film was directed by Leslie Goodwin, based on a story by Leon Abrams and a script by Bernard Schubert. Somehow, the swamp in Massachusetts had become a swamp in Louisiana since the last Mummy movie. I would say that the mummy seems creepier lurching around the Bayou than a New England college town. Stock footage from previous movies appears everywhere and irritated some reviewers. The most startling scene is that in which Ananka rises from the swamp covered in mud. It is both sensuous and creepy. Virginia Christine was worried about being carried around by the often-drunk Lon Chaney, until the director replaced him with a stand-in. She later became well known as Mrs. Olson in the Folgers Coffee commercials. Chaney’s mask is the only surviving example of Jack Pierce’s mummy’s makeup, which is on display at the Experience Music Project Museum in Seattle.