After starting the day by raising the Sun, Celestia was sure that nothing could possibly ruin her day. Unfortunately for her, something had happened to her sister. She really thought Luna would have learned after the last time.
As kids, Twilight and Sunset were best friends, but a tragic accident cut their friendship short. Years later, Twilight investigates the incidents at Canterlot High and comes face to face with what appears to be a literal ghost from her past.
Chasing a mystery into the past, Twilight finds an Equestria that is different from what she remembers. Will she be able to set history back on track by fixing what didn't happen, or is this Equestria destined to take a different path?