Echo Mareau and her brother, Brecker haven't been seeing eye-to-eye. Training together to be defenders of their home, they've fought before; but this time is different. Echo never believed Brecker would connect with a doon, a powerful, dark being that painfully and irreversibly binds a person with a shake of the hand. What's worse, Echo finds out the doon is Belzac, an ancient, dark being who once tried to rule Thildin Valley, home to Echo's family, the elves, and the special horses Echo's dad has cared for all of her life. Echo and her unique horse, Shimmer, must face impossible choices, formidable foes, lung-crushing fears, and the shadows that linger in their own hearts in order to save those they love. With self-loathing, doubt, and bitterness in her heart, Echo may not be able to find the key to victory before it is too late.