Two escaped convicts are found hiding in a rocket ship built by a renegade inventor, who forces them to become the crew for a trip to the Moon. Also on board, as inadvertent stowaways, are his assistant and his secretary; and none of them are aware that the inventor is actually a Lunarian explorer sent to Earth by the dying Lunar civilization.

Herman discovers he’s the new lord of Munster Hall in England. The family sails to Britain, where they receive a tepid welcome from Lady Effigy and Freddie Munster, who throws tantrums because he wasn’t named Lord Munster.