Five years have passed since Twilight Sparkle vanished while visiting her friends at Canterlot High. According to Sunset Shimmer, she never came through the other side of the portal.
Now as her friends and family gather in Ponyville, as they have every year on the anniversary of Twilight's disappearnce, they are shocked when the very last last pony they expected shows up.
Twilight has grown in the five years she has been away, and has quite the story to tell. Of a world held in terror of a monster known as Sin.
And the quest to bring its thousand year reign of terror to an end.