In this 12-chapter action serial from Republic Pictures and director Fred C. Brannon, the mysterious Dr. Vulcan is responsible for a series of murders of prominent scientists, as well as the theft of their scientific breakthroughs, which he sells to foreign powers. It's up to Jeff King (Tristram Coffin), a member of the Science Associates, a gathering of America's greatest thinkers, to discover the identity of Dr. Vulcan and bring him to justice. King is assisted by plucky reporter Glenda Thomas (Mae Clarke) and Associates member Burt Winslow (House Peters Jr.), as well as by the believed-dead Professor Millard (James Craven). Millard has developed a prototype rocket-suit that will allow the wearer to fly through the air at great speeds. Jeff King dons the apparatus to become...King of the Rocket Men!
This was more cheaply produced than the other Republic serials, utilizing much stock footage, and even padding most of one chapter with clips from earlier chapters. Still, this was a big enough hit to spawn a few more "Jet-Pack" serials in the years to come. The final chapter is quite epic, even if a lot of it is repurposed scenes from older movies. Most of the action scenes are the usual fist-fights and driving off of cliffs. It's all entertaining, in a simple way, but not one of the more memorable serials in Republic history, outside of the Rocket Man's image.
