As in Radar Men from the Moon (also released in 1952), much of the screen time for each of the dozen chapters is spent on fistfights and car chases between the heroes and a gang of earthly crooks hired by renegade scientist Dr. Harding and his extraterrestrial colleague Marex to steal and stockpile the Atomic supplies needed for construction of the H-bomb.

He takes to the air in his jet-powered flying suit and helmet to investigate and discovers Martian invaders, led by Marex.

Martin also learns the Martians have Earth accomplices, the traitorous Dr. Harding and two gangsters, Roth and Shane, who bedevil him and his associates, Sue Davis and Bob Wilson.

Marex's Martian aide, Narab, survives the crash and tells Larry where to find the underwater cave with the activated H-bomb.

Source:[1][3] Zombies of the Stratosphere was scripted as a sequel to the successful Radar Men from the Moon serial (1952), which introduced an original flying superhero, Commando Cody, played by George Wallace.

An addition to the "rocket man" back-pack and helmet, and used for the first time in this serial, is a two-way radio about the size of a lunchbox; Larry Martin wears it hanging heavily from his belt when dressed for flying.

As most flying sequences are reused stock footage from earlier "rocket man" serials, the radio usually disappears when Commando Cody is in flight.

[1] Zombies of the Stratosphere reuses the "Republic robot" (somewhat resembling a walking silvery hot-water heater with two ribbed arms that terminate in pincers), along with stock footage of it in action (such as the "bank robbery by robot" scene from Mysterious Doctor Satan) and black-and-white footage from a Republic full color Roy Rogers film.

Their flying effects, using a slightly oversized dummy running along an angled wire, were first used in Republic's serials: Darkest Africa (1936) and with even greater impact in Adventures of Captain Marvel (1941).

(Because of Republic's theatrical contract requirements, Commando Cody was released as twelve weekly movie serial chapters.