Fifth Avenue socialite Irene Bullock needs a "forgotten man" to win a scavenger hunt, and no one is more forgotten than Godfrey Park, who resides in a dump by the East River. Irene hires Godfrey as a servant for her riotously unhinged family, to the chagrin of her spoiled sister, Cornelia, who tries her best to get Godfrey fired. As Irene falls for her new butler, Godfrey turns the tables and teaches the frivolous Bullocks a lesson or two.

When the ancient continent of Mu sank beneath the ocean, some of its inhabitant survived in caverns beneath the sea. Cowboy singer Gene Autry stumbles upon the civilization, now buried beneath his own Radio Ranch. The Muranians have developed technology and weaponry such as television and ray guns. Their rich supply of radium draws unscrupulous speculators from the surface. The peaceful civilization of the Muranians is corrupted by the greed from above, and it becomes Autry's task to prevent all-out war, ideally without disrupting his regular radio show.