The Dark (Guardians Of Time, Bk. 2)

Isabel's brother, Matt, has been named in a Prophecy, not just as a member of the Guard but as their eventual leader. However, the promise of great power in the future does not mean his gifts will come easily. His apprenticeship to Ethan is proving more frustrating than helpful. Of course, the Order never stops their assault on the course of history - and the Guard - so it's only a matter of time before the three are called for battle. When they discover their ageless mentor, Arkarian, has been kidnapped and taken deep into the underworld, the Guard forbids them to travel to the nightmarish place. But a strange connection between Isabel and Arkarian cannot be ignored. Can she convince Matt and Ethan to risk everything and join her on a rescue mission?