Twilight gets a surprise visit from Celestia.
The princess is not herself, gray and weak.
After the visit Twilight and her friends are given the task to save Equestria once again.

On the journey Twilight will learn more about herself and her friends than she ever thought.
They uncover secrets that will set everything in turmoil.
Twilight and her friends also learns of the origin of the proud alicorns of Equestria.