Arnald Arnaldo, collector of interplanetary curios, finds a replica of a long lost planet in a Venusian curio shop. While studying it back on Earth, two figures come to life and go on a rampage. After they return to the globe, Arnaldo takes the globe to Mercury, thinking Earth's atmosphere has awakened the creatures, but the process repeats itself there with four creatures coming to life. On further examination, Arnaldo discovers that the globe isn't a model of Krx, but is the planet itself. Scientists had decided to shrink Krx in size to eliminate the problems it created, but it had drifted off in space before the process was complete. Arnaldo finds the original lab and shrink ray and finishes the job.
Lark, Odar, and Gel are the three Space Musketeers, hired to track down a scientist who crashed on an alien planet with his latest invention. Gel's people can fly and ride wind currents; Odar's people can generate heat and melt their way through mountains; and Lark's people have super-strength. Using these abilities, the three manage to recover the scientist, his weapon, and capture the criminals trying to get to the weapon first.
Thor Larkin has to eject from his ship when trouble arises. He makes a water landing and is captured by fishermen who believe him to be some ancient ancestor of their own people. Taken to scientists, he is used as a test animal for a matter transporter beam.