A year and a half after the events of The Cutie Re-Mark, Starlight Glimmer begins to feel like she has a real home. She has proven to be an excellent pupil for Princess Twilight Sparkle, great friends with the rest of the Mane 6, a hero for all of Equestria and even possesses a bit of romantic feelings shared with Trixie. But when a dark and terrifying being returns in her life, she must suffer a horrible nightmare for not paying her side of a bargain she made long ago.

Now stuck in this constant torture, Starlight must find a way to vanquish this evil entity, before it destroys her life, and takes away everyone she cares about, and everything she worked hard for.