A serious story. Well, as serious as you can get with it being another 'The Conversion Bureau' story.

Edit: Which you can write your own version of if you wish.

Anyway, it's a lot less silly when compared to most of my stories. But still it's very short.

The Conversion Bureau: The White Wall

The Ponies had succeeded in converting every Human into Ponies. However, two strange unstoppable white walls of death are now expanding across Equus and Earth.