The gnome hefts the giant tome situated on his back and then pushes his round spectacles up his protruding nose. He rubs the tip of his nose, knowing that he should really stop studying with his face so close to the books. The skin would sometimes rub off the tip during long hours of recording and study. Specks were moving on down the road, and he produces a spyglass from a loop on his hip. Through the lens, he spots a group of adventurers. He grins from ear-to-ear and gives a hoot, almost losing his balance due to the weight of the book on his back.
"These fellows look like they have purpose! It's time to find out what they're up to!"
A plague has hit the local area.
In humans it affects only the most vulnerable, the children and the very old, and even than it's little more than a summer cold. 24 hours of sniffles and then it's gone, barely noticeable really.
To sheep however it is fatal and the whole economy of the area is in serious trouble. If this keeps up the area could well be facing famine.
Somebody (enter the PCs) must find the rare herbs needed to make a cure.