A gunfighter takes the identity of a murdered judge in order to avenge his death.

The Daily Clarion hires detective story writer Steve Colt to investigate the deaths of a group of scientists working on an atomic rocket development project. Behind the killings is fortune teller Sombra, a spy from an Asian country intent on world domination, who is determined to pilfer the atomic rocket by luring workers from the project to her parlor and killing them with black widow spider venom when they refuse to cooperate.

A man returning home after having fought in the Civil War discovers that corrupt politicians have taken over the county and are terrorizing and shaking down the citizens. He dons the costume of his ancestor, the famous Zorro, and sets out to bring them to justice.

A Martian invader crashes his spaceship conveniently close to the workshop of a scientist who is developing an interplanetary craft. If the extraterrestrial Purple Monster can complete the rocket ship and return to Mars, he will be able to start a full-scale invasion of Earth. Good thing Craig Foster sets out to thwart the Monster's mission!

Jungle-Jim type Johnny Weissmuller helps Professor Blakely look for a missing colleague who is now playing "god" for a bunch of natives.

Jungle Jim battles enemy agents while helping a local tribe relocate from an atomic test bomb site.

Jungle Jim helps an attractive research writer for the British museum clear up the mystery of a tiger cult in Africa while thwarting art thieves and bringing to justice a Nazi war criminal.

Ships disappear on route across the Arctic Sea, and a special submarine is sent to investigate.