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
as Flash Gordon
Carol Hughes
as Dale Arden
Charles Middleton
as Emperor Ming
Anne Gwynne
as Sonja
Frank Shannon
as Dr. Zarkov
John Hamilton
as Professor Gordon
Herbert Rawlinson
as Dr. Frohmann
Tom Chatterton
as Professor Arden
Shirley Deane
as Princess Aura
Lee Powell
as Captain Roka
Roland Drew
as Prince Barin
Don Rowan
as Captain Torch
