((Thought I'd do something for Halloween to get into the spirit of things, no pun intended ^^))
You (Your OC) had volunteered to help prepare the town as Nightmare Night is only a few hours away. With the sun setting you notice the front half a purple filly with a blue mane laying down in the graveyard, though you could not see the rest of its body as it is obstructed from view by a gravestone. Curious and worried for the filly, you go check it out. You then see what was behind the grave.
The filly had appeared to have lost her hindquarters, the only evidence that they were there at all is the jagged line across her torso and the fact that her entrails were hanging down over a hole. In the hole, you can see a broken wood panel and lots of hoof-marks, indicating that she broke out herself and dug her way up to the surface. On the grave, it says: Here lies Innocence.
The D.O.B., D.O.D. and the names of her parents have been worn down too much to be made out.
Innocence: *laying on the ground, smiling at the feeling of the grass and the gentle breeze. She is not showing any signs of hunger at the moment, so it's safe to assume for the time being she isn't hostile*
You now have to figure out what to do with this undead filly. If you don't keep her safe, Innocence could be at risk from other ponies when Nightmare Night starts.