112 years ago, Discord returned, and was subsequently defeated. Prior to his defeat though, Discord broke into Castle Canterlot, in an attempt to destroy Equestria. Eight years later, Twilight Sparkle receives a letter from the princesses, asking her and the other Elements to come to Canterlot, as the princesses do not feel safe. That night, as the sun is setting, and the moon rising, Nightmare Moon makes her presence known yet again.

This is the story of the four years between Nightmare Moon's return, and her downfall, as told by one of the only survivors, Dawn Mother Twilight Sparkle.