In the 23rd year of Discord's initial rule over ponykind, the hidden city of Petrot endures beneath it's magical tarp, an orderly rift in the dangerous, chaotic landscape of the Madlands. There, the Celestial Temple maintains its tenuous hold over the sun and moon, maintaining nature's final regularity.

Two blank-flank fillies, in a foolhardy trip beyond the city, spark a chain of events that will lead them through apocalypses and madness, hordes of wild-ponies and deformed beasts, and to the very ends of the shifting, amniotic landscape that would come to be Equestria.

In their quest to summon the immortal deities of equine pre-history and save the world, these sisters will come to understand Harmony, divinity, and themselves.