An old enemy returns to Equestria while Fluttershy and Rainbow Dash are out of town. When something unusual and unspeakable happens to the Cutie Mark Crusaders, they may be the only ones who can stop it.
After chasing a thief from Canterlot to the desert, Twilight and friends are beset by misfortune. Now, Twilight must delve Equestria's greatest secrets, and discover a truth that even she will wish she hadn't.