A mysterious plague, the Purple Death, ravages the earth. Dr. Zarkov, investigating in his spaceship, finds a ship from planet Mongo seeding the atmosphere with dust. Sure enough, Ming the Merciless is up to his old tricks. So it's back to Mongo for Flash, Dale, and Zarkov.

Science Fiction, Action

Buster Crabbe, Carol Hughes, Charles Middleton, Anne Gwynne, Frank Shannon, John Hamilton