When the Army of Cortes arrived in Mexico, with them came Captain Alvarado, his wife, and their son, Pedro. The Aztec, furious at their invaders retaliated with a cruelty to match Cortes', and finally it was the life of Pedro which was jeopardized. In this story a mission priest helps Pedro find safety with the Zuni Indians. In escaping, they take with them Are, the captain's horse. Are, with a brood of mares, flees, and is discovered by a young Indian boy who has never seen such an animal--horses were not indigenous to the Western Plains. The young Zuni, Suta, learns from Pedro to handle him, and with the advent of horses, a new power is brought to the peaceful tribe, a new means of welding the Zunis in friendship to the stronger Moaches. This story of the introduction of horses to the Western Plains will be of interest to horse enthusiasts and to all those who favor convincing historical adventures.