Jet Power #2

This anthology issue contains two science fiction stories. "The Kroog" follows time travelers who journey back to the prehistoric age to locate Ezra Walters' original time machine, which has been left unguarded among the Kroog—alien machines that have swept across centuries—and they must battle through a jungle of dinosaurs and ancient civilizations to find and destroy it. "Space Ace" features a hero on Titan, moon of Saturn, who discovers an ocean of diamonds but encounters an invisible death force while seeking treasure, and must contend with alien invaders who pursue him for his scientific secrets, including control of rocket-powered boats.