A broken-spirited Spike waits for news of Twilight after an accident lands her in the hospital, dancing on the fine line between recovery and the unspeakable.
Although it is not know to any pony else, Celestia and Luna had a sister-in-law, one that has been forgotten by time and history. But when Twilight Sparkle starts to asks questions, how will (the) Princess Celestia respond?
Luna feels sorrow, pain, deapir, and is lonely. She feels fear and pain, and slowly watch as this eventually turns her into a Nightmare Version of herself. This is the stroy of the transformation and change of Luna into Nightmare Moon.