Kurt Ingston, a rich recluse, invites the doctors who left him a hopeless cripple to his desolate mansion in the swamps as one by one they meet horrible deaths.

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.

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.

Bomba the jungle boy swings into action when an elephant herd is threatened by ivory hunters.