When the trading caravan returns to Ponyville from the Everfree Forest, they bring more than they bargained for. A unique gem, taken from deep within the forest, held balance to the magic of Equestria. With it removed from its resting place, Twilight must heed the words of a strange voice, a voice belonging to a mare whose existence even Celestia is ignorant of, and prevent the destruction of Equestria from the very ponies who inhabit it.