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.
Buster Crabbe
Flash Gordon
Carol Hughes
Dale Arden
Charles Middleton
Emperor Ming
Anne Gwynne
Sonja
Frank Shannon
Dr. Zarkov
John Hamilton
Professor Gordon
Herbert Rawlinson
Dr. Frohmann
Tom Chatterton
Professor Arden
