SEVEN YEARS AGO, Peter and his family survived a deadly scourge of Hail Hounds by retreating to a hidden valley. But when the tracks of the Beasts’ outriders appear, their peaceful life begins to crumble. Deep in the night, the dreaded Ammut emerge from the underground rivers—and destroy everything in sight. Peter barely escapes with his life. Desolate and alone, Peter faces the unknown—until a supernatural warrior appears to offer Peter a chance to get his family back. Now Peter must travel into the caverns of Meremoth in search of an ancient spiritual artifact, the Heart of the Mountain. Between Peter and the peak lie endless miles of marsh and canyon, filled with deadly enemies and unsteady alliances. To reach the end, Peter must summon all the power the Great King has to offer ... and endure the hardest challenge of all—the deception of his own heart.