Under the night of Equestria, dominated by the new queen, Luna or rather her evil self; Nightmare Moon, a princess will rise to fight for the light again and with Celestia banished to the sun and the other princesses of Equestria scattered, it's up to Star Light, the last princess in Equestria, a hybrid dragonpony alicorn to find her way back and attempt to defeat Nightmare Moon.

The elements of harmony are the only way to succeed in this but are hidden away to all but the 6 who failed to claim them originally. But in the darkness Star's own internal struggle rages as she fights to not succumb to her own evil budding inside, anger and mistrust in a dark era could unleash something much more sinister and especially lustful than Nightmare Moon could ever be.
(Gore is exclusive to the story.)