Long before the events of Friendship is Magic, the Eastern Empire was a prosperous country. Discord, seeking greater power, cursed all of its descendants. Five generations later, Featherpen, Fleetfoot, and Vesper must overcome the remnants of their chaotic curse and find a way to reintroduce their people to the outside world.

If the characters aren't clearly defined in the story:
Featherpen is a sea-blue pegasus filly born without wings.
Fleetfoot is a cream Earth colt born without his front legs.
Vesper is a gray unicorn filly born without sight or hearing.