After Nightmare Moon was banished, the bat ponies were society's scrapgoats. Despite Celestia's best efforts, they exiled themselves. Now, a thousand years later, they have settled in the Everfree. When supplies start getting low and Timberwolves grow bolder, Night Lily must leave her home and live among the ponies, waiting for the right time to reveal herself and her people.
Rated teen just to be on the safe side.