Twins Tim and Abi have always been different from their peers, spending their evenings in the attic of their parents' suburban house, poring over reports of the unexplained. Obsessed with photographs of ghostly apparitions, they decide to fake their own, and use it to frighten a girl at school.

But what was only supposed to be a harmless prank sets in motion a deadly and terrifying chain of events that neither of them could have predicted...