"A Gun for Dinosaur" is a thrilling time travel adventure whose action takes place millions of years ago. Reginald Rivers, hunting guide extraordinaire, hears that a time travel machine has been invented and immediately knows what that means: New opportunities to make money! Rivers and his partner Aiyar, hereditary monarch of Janpur, rush to the inventor of the machine only to discover, "There were other hunting guides and no end of scientists, each with his own idea of the right way to use the machine." Despite this competition they persuade the scientists that the money to be made from guiding hunting trips to the ancient past could help support the expensive studies they would conduct with the machine. Soon they are ready for business; many would-be hunters are eager to shoot dinosaurs and add them to their list of kills. "A Gun for Dinosaur" offers a well-researched but thoroughly exciting adventure in the era when Tyrannosaurs and Triceratopsians roamed the Earth.