Goodmen, Gentles, my Lords, in the best exemplification of the heroic stories you have found the Villain, battled him and his minions, plundered them of their treasure then returned victorious. But Now you discover a greater horror.. Lawyers.. Lawyers...
The modern definition of festival has four parts: 1. a day or time of religious or other celebration, marked by feasting, ceremonies, or other observances: the festival of Christmas; a Roman festival. 2. a periodic commemoration, anniversary, or celebration: an annual strawberry festival. 3. a period or program of festive activities, cultural events, or entertainment: a music festival. 4. gaiety; revelry; merrymaking. In the later eras of the European Rennaissance (early modern) there was an additional meaning; 5. The marking of important events in the life of a princely dynasty, such as marriage, the birth or christening of an heir, a coronation or a funeral, or the traveling to a new country/ state/ city.
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.