Skandar and the chaos trials

"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 in peril, all fingers point in one direction. As suspicions grow and dark forces assemble, Skandar must decide where his loyalties lie. How far is he willing to go--for Kenna, and for the Eyrie?"--Provided by publisher.