Nightmare Night, the annual evening celebration to pay tribute to the nocturne is upon Ponyville once again. But this Nightmare Night happens to fall on the same day as another tradition, a far darker one that most residents are completely unaware of.

On the eve of the festivities, a great evil enters Equestria and soon the terror becomes very real. Twilight and her friends must work to understand the source of this darkness quickly and they have but the space of a single night...