In an alternate 1920s timeline, Ace pilot "Captain Stratosphere" Jack McGraw leads an intrepid crew against sinister forces of evil set to take over the world. Using an experimental airship, Daedalus II, the crew plays a dangerous game of cat and mouse with the Astrum Argentum and their commander Maria Blutig, from the eastern US to the Caribbean, to the wild green jungles of the Amazon. They encounter saboteurs, sky pirates, a powerful voodoo priest, man-eating crocodiles, a giant treasure-guarding octopus, rocket-zombies, and a tribe of jungle natives living in a majestic wooden city in the tree canopy, culminating in a ferocious battle against Blutig and her master, the sorcerer Aleister Crowley. This four-part serial adapted from the original comic strip uses a retro radio style of delivery, including the fictional Gold Star Essentials commercial sponsor, a crushed monophonic sound mix and vintage wire crackle.