Sixteen-year-old Canny Mochrie's holiday takes a turn when she stumbles upon a mysterious and enchanting valley, occupied almost entirely by children who can perform a special type of magic that tells things how to be stronger and better than they already are. As Canny studies the magic more carefully, she realizes that she not only understands it—she can perform the magic, too, so well that it feels like it has always been a part of her. With the help of an alluring seventeen-year-old boy who is held hostage by a spell that is now more powerful than the people who first placed it, Canny figures out the secrets of this valley and of her own past.