Princess Celestia has invited Twilight and her friends to spend Hearth's Warming Eve with her and Luna at Canterlot. But when Twilight is arrested for a crime she didn't commit, Luna is convinced that it has something to do with why she became Nightmare Moon so long ago. Twilight and Luna must clear Twilight's name and confront the secret behind Nightmare Moon before she takes over again, embarking on a journey through a frozen forest into the deepest reaches of their own fears. A romantic horror story for the holidays!