He longs to know more about her, but Papá won't talk. So when Max uncovers a buried family secret--involving an underground network of guardians who lead people fleeing a neighboring country to safety--he decides to seek answers on his own.With a treasured compass, a mysterious stone rubbing, and Buelo's legend as his only guides, he sets out on a perilous quest to discover if he is true of heart and what the future holds.