Soter the Light Horse has finally broken the Curse of Evil on the world of Equus, fulfilling the ancient Prophecy. But the war between good and evil is far from over. Despite his defeat, Abaddon the Dark Horse will use all his power to seek his revenge by destroying the mortal equines.

​Meanwhile, Stone, Lightning, and the rest of Soter's faithful apprentices begin their own mission to recruit mustangs and other equines to join Soter's Herd. But such a task is not going to be easy, for there are still enemies seeking to trample out Soter's memory forever. Among them is Wolf, King Wildfire's ruthless deputy, who carries out orders in hunting down anyone who dares speak Soter's name. If they are to survive the challenges ahead, Stone and his friends must stand firm and persevere.