The forest of HalÃ«fas is a strange place indeed. It has long been inhabited by the forest elves, a race of elves descended from the high elves that have lived for over 9000 years isolated there. This wood is patroled by a groupe of expert rangers who know the forest well, Tred lightly and unthreateningly here for you may find your end in Hathil’S arrow.
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.