Just shy of two decades before the return of Nightmare Moon, Princess Celestia received an ultimatum from the Griffon Kingdom's recently ascended heir: Concede a part of Equestria, or prepare for war.
The Princess chose neither, instead ordering her engineers to create a craft great enough to terrify the griffons and put an end to the war before it could have even begun. Two years after her order, Equestria had constructed its greatest airship yet, the Lux Aeterna.
With no time to spare, the craft was sent on its way almost immediately after its construction was finished, carrying with it five hundred esteemed guests and nearly a hundred crewponies. However, such a massive endeavour piqued the interest of not just the griffons', but also of an ancient presence nopony could foresee, let alone contend with...
(Release schedule: 2 chapters / day.)
Edited by Jinxed and Equimorto.
Loosely based on Iron Maiden's Empire of the Clouds.
