In the near future, Earth has some interaction with alien worlds, and so the government has named brilliant scientist Commando Cody (Judd Holdren) as the Sky Marshal of the Universe. He is charged with dealing with interplanetary menaces, particularly the machinations of the Ruler of the Galaxy (Gregory Gaye), who uses powerful alien weaponry to try and conquer the Earth. Cody, along with his two sidekicks, uses a fantastic rocket suit and spaceship to battle the Ruler and his minions
This fourth rocket man serial was originally intended to be a TV series. The first three episodes were filmed (with William Schallert as one of Cody's sidekicks), but then production was put on hold, and Republic filmed the 1952 serial Zombies of the Stratosphere. After that was finished, production resumed on this, with Richard Crane replacing Schallert. After its completion, Republic decided to release it theatrically as a serial instead of a TV series, partially due to pressure from technicians' unions which stated that crews were paid more for theatrical productions. Still, Republic did eventually release this as a syndicated TV series in 1955.
This is both sillier and more creative than the previous rocket man serials. Cody wears a domino mask and a jaunty little cap whenever he's not in his bulky helmet, ostensibly due to security reasons. The villains wear a variety of silly hats, as well. There are rocket flights in space and to other worlds, and the Republic robot shows up yet again. There is still the traditional re-use of footage from previous serials and movies, even back to The Purple Monster Strikes from 1945. Each chapter runs a solid 30 minutes, meaning the entire thing took 6 hours to watch. Since this was intended to be a TV show, the chapters are more like episodes, with self-contained dilemmas that are resolved without any cliffhanger endings. This wasn't the last serial released, as that would be 1956's Blazing the Overland Trail.
