Doctor Bryant (James Craven) has been making some remarkable breakthroughs in the use of atomic energy as a weapon. This draws the attention of Mota (Gregory Gaye), a Martian sent to Earth to help orchestrate domination of the planet. Mota will conquer Earth in the name of the "Supreme Ruler of the Universe", and if Bryant will help in the effort, he will be named the governor of Earth in the Martians' name. It's up to Kent Fowler (Walter Reed), the head of a small aviation and security firm, to stop Mota and Bryant and their fiendish plans.

One of the worst of the Republic serials, this was a cheap stitch job using loads of footage from previous serials and other Republic pictures. Even the Martian costume, only briefly worn by Mota, was the same from their previous effort The Purple Monster Strikes. Almost all of the outdoor action scenes, whether it's a car chase, or flying vehicles, or buildings exploding, are lifted from other films. They were so cheap that they even reused the same exact footage more than once in the same movie, simply reversing the image from right to left to try and make it look like a new shot.

The hero played by Reed is bland, although it becomes unintentionally hilarious how he makes his miraculous escapes from the chapter-ending cliffhangers, which almost always involve him jumping from a vehicle of some sort. Better yet are the aerial escapes, such as a plane crash that he survives by jumping from the cockpit into a tree as the plane hits the ground, or when he survives injury-free from a fall from another plane by landing in a pile of hay at a farm. Still, this silliness doesn't really warrant the nearly 3 hours it takes to watch the whole thing, so only the most ardent serial fanatics need apply.