After the disappearance of the ponies of Trottingham, the Mane 6 go to investigate, along with Princess Celestia, who has taken a personal interest in the case. After investigating, it is revealed that what happened has ties to the origins of Equestria, and the princesses. Along the way, friendships are tested, allies are found, enemies are discovered, and a villain as old as Equestria makes himself known...