Betty and the girls confront the source of their nightmares, and discover its connection to the Cloisters.
The girls spend the night searching the woods for the cabin in their nightmares. What they find is stranger than their dreams, and maybe more dangerous.
A third shared nightmare confounds the school. Betty and her friends may have found another missing girl.
Betty discovers another missing girl and why no one remembers her. The strange lichen she and Cat found is much older than they thought.