"Regan loves, and is loved, though her school-friend situation has become complicated, of late. When she suddenly finds herself thrust through a doorway that asks her to "Be Sure" before swallowing her whole, Regan must learn to live in a world filled with centaurs, kelpies, and other magical equines-a world that expects its human visitors to step up and be heroes. But after embracing her time with the herd, Regan discovers that not all forms of heroism...