You noticed that ponies in ponyville have been acting...strangely? You've noticed that many ponies have symptoms such as aggression, strange spots on their hooves and it seemed dementia, because some of them behaved as if they weren't responsible for their actions. One day you were walking calmly through ponyville until you heard some munching sounds from around the corner. Looking there, you saw how an earth pony was eating another already seemingly half-decomposed pony. The one who was currently munching viciously over a half-decomposed body looked like a living corpse herself, and seemed worms coming out of her body...

what's going on?...