The House of Eternal Mercy

From the introduction:

Several local villagers have gone missing, one of which is a local lord’s trusted farmhand. Unbeknownst to all, an evil monk has returned from the grave and is terrorizing the countryside. Caravans traveling at night along the road have spotted lone individuals matching the description of the missing, wandering near an old ruined temple. The player characters are hired to investigate these strange sightings and perhaps find the missing parties.