Thirteen-year-old Skandar Smith has always wanted to be a Unicorn rider, but when the mysterious Weaver steals the most powerful unicorn in the world, Skandar must face sky battles, ancient secrets, and bloodthirsty unicorns in order to save his island.

To survive their third year of training, Skandar and his friends must complete a series of terrifying trials across the Island's elemental zones. Friendships, allegiances, and rider-unicorn bonds will be pushed to the limit--only the strongest will make it. Meanwhile, Skandar's sister, Kenna, has finally reached the Eyrie. But with a forged bond to a wild unicorn, she is alienated and alone. And when a terrible discovery puts the future of the Island...