Years after the founding of the Soter Herd, a mysterious stallion with supernatural powers appears, captivating equines around the world. Many are convinced that the Light Horse has finally returned, but Aurora, Soter's half-sister, and her mate Midnight have suspicions.
Upon a shocking discovery, Aurora and her family join forces with other equines to uncover a secret plot to take control all of Equus. But they are about to be hurled into what will become the last, epic battle between the Light Horse and the Dark Horse. This time, only one will claim the title "King of Equus".