After the events of the Fall Formal, Twilight needs some alone time. So, after forcing a Pinkie Promise from her friends that they wouldn't follow her, she heads for the Castle of the Two Sisters.

Along the way however, she meets a strange mare named Willow. Not sure why, but feeling that it is right, Twilight follows her into a journey that will change her in ways she could never have imagined.

The Everfree will have its queen, and Equestria will know a terror unlike any before it.