The Phantom Empire (1935 film serial)

The Phantom Empire is a serial film in twelve parts, released in 1935 by Mascot Pictures, which details the discovery by Gene Autry, the Singing Cowboy, and his assistants of an underground remnant of Mu known as the Scientific City of Murania beneath Autry's Radio Ranch in New Mexico. A highly abbreviated version of the serial, running seventy minutes (compared to the over four-hour run-time of the full serial), was released as a feature film in 1940 under the title Men With Steel Faces (or Radio Ranch).