"Danger lurks as the air grows colder and threats lie in the shadows at every turn. While the rest of their fellowship seeks safety, Bea and Cad team up with a small group of survivors to travel to the Citadel of Knowledge, pursuing answers to their world's darkest mysteries. But their journey reveals even more secrets. Until an unexpected ally shines a light in the darkness, providing a clue to a mystery from long ago...and a beacon of hope for the future."-- Provided by publisher.

Chiefly illustrations.