Abbott and Costello Meet the Monsters!

Two Americans stranded in Cairo overhear Dr. Gustav Zoomer discuss Klaris, the mummy who guards the Tomb of Princess Ara, and a sacred medallion that supposedly points to treasure. The discovery promises wealth but also danger from Klaris' followers.

Followers of Klaris, led by Semu, and Madame Rontru overhear the same conversation and begin to plot how to seize the mummy and its treasure. Their plan sets up betrayal and danger as the medallion becomes the key to everything.

They go to Dr. Zoomer's house to apply for the job of accompanying the mummy back to America. They hope to become part of the expedition and secure a share of the treasure. The encounter starts their direct involvement with Klaris' fate.

Just before Abbott and Costello arrive, Semu's men ambush the doctor's house, murder Zoomer, and steal Klaris. The medallion is left behind, setting the stage for the Americans to stumble into the hunt.

The medallion is found by Abbott and Costello, and they try to sell it. Rontru offers them $100, but Abbott suspects its true value and asks for $5,000, which Rontru agrees to pay.

Rontru directs them to meet at the Cairo Café for the deal, and a waiter warns that the medallion is cursed. In the scramble to finalize the exchange, the medallion ends up inside Costello's hamburger.

Rontru drags them to a doctor's office to view the medallion under a fluoroscope. She cannot read the inscriptions, which are in hieroglyphics, leaving the meaning unclear.

Semu arrives, posing as an archaeologist, and offers to guide them all to the tomb. Meanwhile, Semu's followers have restored life to Klaris, increasing the danger and urgency.

The group arrives at the tomb, and Costello learns Semu's plan to murder them all to secure the treasure. Rontru's schemes begin to intersect with Semu's as tensions rise.

Rontru captures Semu, and Charlie disguises himself as a mummy to enter the temple. Abbott also disguises himself as a mummy, and the two of them team up to rescue Semu.

In a climactic moment, the three mummies are in the same place, and the dynamite Rontru intends to use detonates. Klaris is killed, and the treasure is revealed, ending the immediate threat.

Abbott and Costello persuade Semu to turn the temple into a nightclub to preserve Klaris's legend rather than loot the tomb. The treasure remains at rest while the legend of Klaris continues in an unlikely setting.