Local temple (agricultural type goddess) been generally lax and living it up, not actually doing much work in the way of religion. One of the PCs knows someone in this temple - is asked to do a favour. The major temple of the same religion is sending round a small group to "inspect" all the little provincial places. The report will be both a financial one (audit) and a load of interviews with the congregation. If the report gets done properly (ie truthfully) all the priests are in big trouble.
What the PCs are asked to do is to help alter the way the report gets done. The problem is that a report has to get done, that killing the visitors is a massive no go, and that the PCs are going to have to alter the perception of the temple and the surroundings without the visitors realising.
In the version we ran, the PCs got a hand from the priests in that the priests took care of the congregation (by buying them all drinks etc) and the party only had to deal with the visitors. They did this by finding out some background (5 visitors), and then seducing 2, getting 1 blind drunk, bribing one, and blackmailing the last. Thus the report was written by the right people, and no- one's suspicions were raised.