A secret agent goes after the gang that stole the crown jewels of a European monarchy.

When a deadly Nitron ray strikes Earth, Flash Gordon and his friends travel to Mars to battle Ming the Merciless and his new ally Queen Azura.

Edited version of the 1939 Universal serial "Buck Rogers." A 20th Century pilot named Buck Rogers and his young friend Buddy Wade awake from 500 years in suspended animation to find that the world has been taken over by the outlaw army of Killer Kane.