It's been 1000 years since Princess Luna overruled her sister Princess Celestia in the grand battle after becoming Nightmare Moon and banished her to Erebus, the deepest part of Tartarus known to all of Equestria. Now nearly all have forgotten her lost sister due to her heavy hand in making sure that the Night is worshipped and loved, though she still raises the Sun on the daily to keep the world from dying out.

Yet the power of the Sun is beginning to wane, and Princess Luna decides to send her current student, a bat unicorn named Twilight Sparkle to seek out why the Sun is dying. It just might end up being her downfall.