House of the Star by Caitlin Brennan - Paperback

Elen is a princess of the kingdom of Ymbria. Her greatest wish is to become a rider of worldrunners: the magical horses that are the only safe way to travel the roads through the worlds of Faerie. Now Elen has the chance to fulfill her dream at last, but the price is much too high.

To become a worldrider, Elen must journey to the House of the Star on Earth, the Arizona ranch where the worldrunners live and breed. There, she must try to forge a peace with her people’s worst enemy—a traitor from the world of Caledon—and end the war that has been tearing their worlds apart for centuries. If Elen doesn’t succeed, the Master of the House of the Star will close both Ymbria and Caledon off from the worldroads forever. Can the wisdom of a worldrunner named Blanca help Elen in her quest to save her world?