In the town of Mapleton, Massachusetts, Professor Stephen Banning (Dick Foran) entertains his family with the story of how he defeated the living mummy Kharis (Lon Chaney Jr.) thirty years before. But in Egypt, Andoheb (George Zucco) explains the same story to his follower Mehemet Bey (Turhan Bey) from his point of view. After teaching Mehemet how to use the sacred tana leaves to revive mummies, Andoheb dies. Mehemet Bey and Kharis leave Egypt to find the Banning family in Massachusetts.
Bey takes the caretaker job at the Madison Cemetery and gives the brew to Kharis, who sets out to avenge the desecration of Ananka’s Tomb. He kills Professor Banning as he prepares for bed. The coroner (Emmett Vogan) and the Sheriff (Cliff Clark) are stymied. Banning’s old friend Babe Hanson (Wallace Ford) arrives when he hears of Banning’s death. Jane Banning (Mary Gordon), Steve’s sister, is killed, and Hanson is sure it was the work of the mummy. Obviously, the Coroner and the Sheriff don’t believe it. Babe tells the story to a reporter in a bar but is then killed by Kharis himself. Doctor John Banning (John Hubbard) asks for help from Professor Norman (Frank Reicher) to find out the meaning of the gray marks on the victims’ throats and it turns out to be mummy dust.
Meanwhile, Mehemet Bey has his own plans. He knows that Doctor Banning is preparing to marry Isobel Evans (Elyse Knox), but Bey is obsessed with her and orders Kharis to seize her for him. The mummy enters the Doctor’s house and abducts the girl and takes her to the caretaker’s hut. Bey tells her that she will become the bride of the High Priest of Karnak and will bear him an heir to the royal line, a singular honor that she doesn’t much care for.
The townspeople confront Bey outside the hut. Kharis flees with Isobel and Bey tries to shoot Banner but is shot by the Sheriff. Kharis is spotted on his way to the Banning estate and a torch-bearing mob follows him. Inside, Banning and Kharis battle. Banning rescues Isobel, but his torch sets fire to the house. It’s beginning to look like a Frankenstein movie. John and Isobel escape with the aid of the Sheriff and Coroner, and the monster dies in the flames. Manning and Isobel marry shortly because he has been drafted.
The film was directed by Harold Young. Lon Chaney would play the mummy in two more sequels. George Robinson was director of photography. There was a lot of stock footage from other Universal monster movies. It was unfavorably compared to other films, like The Wolf Man. If it is thirty years later than The Mummy’s Hand (1940), it should be taking place in 1970, but it is set during World War II. The opening music is the same as that in The Wolf Man.