A pony who is called Anonymous became a mass murderer, in order to end Celestia's rule. Not even the best of Equestria can catch him, or even find his identity.

What happens when a pony finds a book that allows them to control destiny?

"Will you rise with us, to stop the tyrant princess? Will you fight for Equality of all us ponies? Or will you fight for Twilight Sparkle, a new ruler of Equestria, to fight for that tyrant? Join us, let us bring Equality to all of us!"