Dimble Stumpwater is this worlds last best hope for expedient library book returns
a very useful exotic weapon
The PCs traveling through the mountain end up in the the small village of Bitterfruit, this tiny village is the epitome of paradise, but even paradise has its secrets.
A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.