Kemlo, captain of Space scouts, and his young friend Krillie receive a visit from two Earth children, Dane and Lesa, Krillie's cousins. Lesa is quite prepared to be thrilled by all that she sees on Satellite Belt K, but Dane sneers at everything - especially at the mechanical horse in the games-room. he boasts of his own prowess, and is heard by their science engineering master from Earth, who determines to teach him a lesson and at the same time to evolve, with the help of Kemlo and the other troop leaders, a new mechanical wonder, a New World Pegasus, a horse that can gallop in Space...