See, this is why M.R. James is one of my heroes — from Ghost Stories of an Antiquary:

“Also there was the lady who, on locking her bedroom door in a strange house, heard a thin voice among the bed-curtains say, ‘Now we’re shut in for the night.'”

Oh boy. If the very idea of that thin voice, that disembodied (we hope!) hidden secretive confident voice, makes you afraid – if someone (I, say) were to sneak up behind you right now and say “Now we’re shut in for the night,” and that would send you straight to the ceiling, why, you and I have a lot in common.