Ever since Luna's release from Nightmare Moon, Princess Luna has kept a secret from all of those under her rule. The Bat Ponies, the mysterious servants to Princess Luna, have for years kept the Nightmare Forces at bay by using Luna's magic, now face an even greater threat as the Nightmare Forces begin to kidnap and possess kidnapped fillies to bolster their forces. And with the new coronation of Princess Twilight, Princess Luna can no longer enchant the Bat Ponies nearly as often as she used to. Times are tough, but one brave young filly may be the key to their ultimate victory.