There exists two Equestrias, Diurnal and Nocturnal, one ruled by Celestia and the other Nightmare Moon. Though they are intertwined, their cultures are worlds apart. Neither are allowed, by law, to see or interact with the other. Concordia, a cross-border agency, enforces this law with extreme prejudice. Break the law and face severe consequences.

Rarity, a private detective, has lived all her life in Diurnal Ponyville with this as a reality.

Ruby Becker, a human tourist, newly arrived in the city, has yet to experience the bizarre nature of the dual cities for herself.

Twilight Sparkle, a member of the Royal Inquisition, Nightmare Moon’s secret police, must work constantly with the knowledge that even she is not above Concordia.

All three soon get entangled in a conspiracy far stranger than this dual reality, one that involves the existence of the legendary Hippolyta, a third Equestria that lurks in the shadows between the ponies and the ponies.

(Inspired by China Mieville's novel, The City and the City).

Initial proof-reading by MindAssassin.