Castle Avamir — Kathleen Duey

It has been a long, hard winter, and the Gypsies are glad to be leaving Lord Levin's mountains for the sunny plains of Lord Kaybale's lands. But that means time is running out for Heart. The old stories say that Castle Avamir is higher than the clouds, deep in a valley, under the stars, and over the moon.

It makes no sense -- but if Heart can't solve the riddle, she might never find a safe haven for her beloved unicorns.