A little over a thousand years ago, it was no secret that very few, if any ponies, cared for Luna or her night sky, preferring Celestia's love and light to the darker Princess's more mysterious ways. However, these accounts aren't as accurate as historians make them out to be. For, in truth, one thousand years ago lived a pony by the name of Crescent Eclipse. As she grew, Crescent became Equestria's first real astronomer, charting the heavens as night settled over the land. As such, she was the first to notice as the nighttime began to get colder, and the stars and moon, which had once been her nightly companions, seemed to become bitter and distant.

Upon taking note of this, Crescent set out to find out what was wrong, and over a thousand years later, Luna is rummaging through some older books in the Canterlot Library when she discovers a very old, long abandoned journal hidden behind several other books. Curious, Luna takes the journal and begins to read it. What she finds inside shocks her to her very core, making her reassess everything she thought she knew and remembered about the days leading up to her turning into Nightmare Moon and being banished.