Four explorers are summoned to Peru by the brilliant physicist Dr Thorkel. They discover a rich source of radium and a half-mad Thorkel who shrinks them down to one-fifth their normal size when they threaten to stop his unorthodox experimentation.
The people of Sadok are besieged by a terrible, man-eating, giant Cyclops that has ravaged the countryside and consumed many of its people. Atlas arrives at Sadok with the intent to defeat the monster and help the people, but is faced with another type of battle. The evil Queen Capys has set her sights upon Atlas and decides to try everything in her power to take him as her own. Now Atlas must try to defeat two enemies as well as rescue the infant descendant of Ulysses from being eaten by the Cyclops.