The Mummy's Tomb is a 1942 American horror film directed by Harold Young and starring Lon Chaney Jr. as Kharis the mummy. Taking place 30 years after the events of The Mummy's Hand, where Andoheb (George Zucco) has survived and plans revenge on Stephen Banning (Dick Foran) and his entire family in Mapleton, Massachusetts. With the help of the high priest Mehemet Bey (Turhan Bey), Andoheb and the mummy Kharis (Lon Chaney Jr.) Bey takes up a job as a caretaker of a graveyard. At the first full moon, the mummy is fed tanna leaves which allow him to break into the Banning residence and kill the now elderly Stephen. Banning's son then seeks assistance from Babe Hanson (Wallace Ford), one of the members of the original Banning expedition to Egypt to stop Andoheb and Kharis.
Lon Chaney Jr. had renewed his contract with Universal Pictures in 1942 and had his first role as the mummy Kharis in The Mummy's Tomb, a role he would reprise in the film's sequels The Mummy's Curse and The Mummy's Ghost. The film was shot on June 1 and ended in mid-June 1942, not including footage taken from the previous film in the series The Mummy's Hand as well as Frankenstein.
The Mummy's Tomb picks up the story of Kharis thirty years after the conclusion of The Mummy's Hand. One evening in the fictional town of his Mapleton, Massachusetts, Steve Banning recounts the story of Kharis to his family and evening guests in his home. As he concludes his narrative of the successful destruction of the creature, the scene switches back to the tombs of Egypt. Surviving their supposed demise, Andoheb explains the legend of Kharis to his follower, Mehemet Bey. After passing on the instructions for the use of the tana leaves, and assigning the task of terminating the remaining members of the Banning expedition and their descendants, Andoheb expires. Bey and Kharis leave Egypt for the journey to the United States.
Bey takes the caretaker's job at the Mapleton cemetery, sets up shop, and administers the tana brew to Kharis. The monster sets out to avenge the desecration of Ananka's tomb. His first victim is Stephen Banning, whom the creature kills as the aging archaeologist prepares for bed. As the sheriff and coroner can't come up with a lead to the killer, newspapermen converge on Mapleton to learn more about the story. Babe Hanson (Wallace Ford) arrives on the scene after learning of his friend's death. When Jane Banning (Mary Gordon), Steve's sister, is killed, Hanson is convinced it is the work of a mummy. Meeting with the sheriff and coroner, Hanson is unable to convince them of the identity of the culprit. He tells his story to a newspaperman at the local bar, but is himself dispatched by Kharis almost immediately afterwards. Dr. John Banning (John Hubbard) enlists the help of Professor Norman to solve the puzzle of the "grayish mark" found on the victims' throats. Norman's test results prove that Hanson was right: the substance was indeed mold from a mummy.
Meanwhile, Bey has plans of his own. Knowing that Banning and his girlfriend, Isobel Evans are planning to marry, he sets out to disrupt their nuptials. Bey himself has become smitten with Isobel, and sends Kharis on a mission to bring her to him. Kharis initially balks, but finally adheres to Bey's command. In the dark of the night, the monster stealthily enters the Evans's home and abducts the fainting girl to the cemetery caretaker's hut. Bey unveils his plan to the reluctant Isobel, that she is to become his bride, as a "High Priest of Karnak", and bear him an heir to the royal line. Banning and the rest of the townspeople have become convinced that their recent Egyptian immigrant may be involved in the crimes. Arriving in force, they confront Bey outside the hut. Kharis slips away with Isobel unbeknownst to the horde, and Bey attempts to shoot Banning, but is himself gunned down by the sheriff. The creature is observed heading toward the Banning estate, and the group begins pursuit, many bearing torches. Inside the home, Banning holds Kharis at bay with a torch while he rescues Isobel from the mummy's grasp, but inadvertently sets fire to some curtains. With the aid of the sheriff and coroner, John and Isobel escape via a trellis as Kharis pursues them out onto the upstairs balcony. The townspeople keep the mummy from similarly escaping by hurling additional torches at him, and the monster perishes in the flames of the thoroughly consumed house. Banning and Isobel wed in short order, as he has received his draft notice and is due to report for his tour of duty in World War II.