Equestria has been at peace for the past Five Hundred years, due to the strong Rule of Prime Celest. Birthed from the Hive Turtle Brom and gifted with the soul of the Sun. Wielding her immense power, Celest has brokered peace through force with Equestria's potential enemies. Her beloved student, Twilight sparkle has been with the Prime her entire life and her feelings have slowly shifted through time. One day before the Summer Sunset Celebration, Twilight is gifted an old book. One telling a much different history then she'd believed.

Celest-Tia? Nightmare moon? Two rulers of Equestria?

Now, Twilight Sparkle is forced to call everything she thought about her Solar Princess into question as a new threat to Equestria looms over the horizon. Now Twilight has to race the clock to perhaps Save the Lost Princess of Equestria before Celest can destroy the only link to her own forgotten past.