Johnny Sokko and His Flying Robot: 21 - The Terrifying Space Mummy

Millerman (called the Space Mummy in the American version) has poisoned the water supply so anyone who drinks it is turned into a mummy. Millerman and the BF Syndicate are hiding out in a convent disguised as nuns. Agent U5 is captured and Minami dresses as a nun to rescue her. Mari storms the convent with guns blazing to rescue them. Giant Robo must fight a revived Dorogon, which Millerman can cause to grow and shrink in size with the aid of a special device.