Young Celestia has gone into hiding in the underbelly of Equestria. Through his vile scheming, Discord has driven her out of Canterlot Castle, engineering a civil war; Luna, her mind and soul poisoned by Discord, has turned into Nightmare Moon. Sooner or later, Celestia must face what she knows is her destiny: to confront and banish her own sister, before the advent of Eternal Night.

The year is 1886. Brilliant, but eccentric master detective Twilock Sparkle enlists the help of her friend and partner Dr Spikeson to solve her most challenging case yet. But this time, their adversary might just be out of their league...

‘Have you ever,’ she started, ‘broken a promise you made?’

Celestia and Luna live a carefree childhood at Canterlot Castle, but its end approaches far too quickly — no matter how much they struggle, they find themselves drifting apart. And without their noticing, a new evil rises that could drive a wedge between them for good...