As far as most ponies are concerned, The Shadowbolts do not exist. They exist only as stories and rumors, something associated with Nightmare Moon and the return of Princess Luna.
Starry Skies is a bat pony and Shadowbolt field agent. Her job is to help keep Equestria safe by stopping some threats before the public even knows about it.
When rumors begin to spread that a cult of some kind is planning to summon a great evil, it is up to Starry Skies and her partner Mimic to find out if it is true, and if so, to make sure that they do not succeed.
Is there actually a cult? Can Star stop their plans? And what happens when her professional and personal life cross?