"Please, there must be something you can do. Oh if he'd just managed to keep his eyes open, two more minutes would have been enough."
Caution: contains mature content regarding the gruesome ecology of a parasitic beetle.
A terrible monster. A thing of nightmares. Tales of the creature shake the core of the most sturdy and chill the spine of all who hear. They say, "Be careful who your friends are. They may just want you for your body." They were right.
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.