Nightmare Moon and her followers were banished to the Moon almost a thousand years ago, but their war on Equestria never ceased. For centuries, they have rained down meteoric attacks from the skies in events known as 'starfalls.' When one such event forever disrupts the course of Rainbow Dash's life, she'll be sent on the run across a very different Equestria in search of the only other ponies who can help her take the fight back to Nightmare Moon, far above the sky in her dark city.