Luna is through with Celestia making excuses for why ponies don't show her the love and admiration she deserves as co-ruler of all Equestria.

But when a towering monster appears and tells Luna that she can bring her sister to heel and be properly appreciated, Luna remains wary. She is no fool like Sombra, to fall prey to the darkness.

But this "Nightmare Moon" knows too much. Who is she? Why does she bear Luna's mark? And why is she so confident about the course the future will take?