After a UFO sighting, a mysterious phantom in a bizarre outfit starts attacking people in San Fernando Valley.

Lee Garvin has eloped with the daughter of a railroad man who didn’t approve of the marriage. Hoppy steps in when the young man is framed for murder.

Claire Forrest seeks her kidnapped scientist father, hidden somewhere on Mystery Island. He is held and forced to work on diabolical inventions by Captain Mephisto, a costumed villain.

Frontiersman Kit Carson fights off Indian attacks on the trail to California.