Hell has an infinite library. Twilight wants to use that library. There goes the neighborhood. Yep, right out the door, and it’s taking the couch with it.
When one fateful search through the Everfree Forest leads Rarity to a secret library inhabited by the spirit of an ancient alicorn princess, she realises that it may be time to start believing in fairy tales.
700 years have passed since the night Nightmare Moon defeated her sister Celestia and cast her to far off lands, stripping her of power. Now, the hate in the younger sister's heart has faded, and she has brought Celestia back to Equestria.