The Phantom Empire is a 1935 American Western (genre) film series directed by Otto Brower and B.

Reeves Eason and starring Gene Autry, Frankie Dallo, and Betsy King Roth.

Synopsis:
When the ancient continent of Mu sank to the bottom of the ocean, some of its inhabitants survived in underwater caves.

Cowboy singer Gene Autry accidentally discovers this civilization buried beneath his radio ranch.

The Muranians developed technology and weapons such as television and ray guns.

Their rich supply of radium attracts unscrupulous speculators from the surface.

The peaceful civilization of the Muranians is corrupted by the greed of the upper echelons, and Autry's mission is to prevent all-out war.