Luna discovers a vast and ancient being approaching Equus. When she and Celestia go to meet it, they see into the early dawn and eternal twilight of their universe.
Where did Celestia disappear to, the night of the 1,000th summer sun celebration? Why didn't Nightmare Moon simply kill the mane six? What was The Nightmare willing to do in its hatred, and The Princess willing to do for her beloved little ponies?...
To save Rarity, Twilight and her friends must follow her to a war-torn world struggling to survive an eternal winter night, where Hearth's Warming never happened.
