...do the players know? I'm thinking of just wrapping them in the equivalent of boogeyman tales, with each player learning as a child that you just avoided the places. The disappearance of the young girl could be something their grandparents told them about over a fire one night as a ghost story, which would make the discovery of the blanket a little chilling.
Thoughts?
I think with the sound tubes in the beginning of the cairn stories about wailing banshees would be very appropriate. You could also add some fresh kills the wolves made to a few of the room descriptions to realy creep your players out. When I was younger me and some friends went out investigating some "haunted" places just out of town. After climbing up a good sized sandstone boulder we found the torn to hell and back remains of a rabbit or something, scared the crap out of us tell we figured out all the blood and everything was coming out of a bird nest.
I hadn't thought of the sound tubes being mistaken for banshees. Thanks! Just the thing to creep the hell out of kids on a cold autumn night.