A 1966 feature length compilation of the first half of the 1940 serial Flash Gordon Conquers the Universe. When the Earth is attack by a mysterious substance causing death and leaving the victim purple, Dr. Zarkov, Flash Gordon and Dale Arden discover the deaths are caused by one of Ming's spaceships from the planet Mongo. They go to the planet to bring an antidote back to the Earth and thwart Ming's schemes.