When Adam Bradford's sister goes missing he drops everything to assist the police, travelling up to the isolated village where she lived.
When he arrives at her cottage, however, he discovers a life in disarray and a bedroom filled with cryptic notes and mysterious blurred photographs.
At first he puts this obsession down to some kind of psychological disorder, but after he experiences a series of disturbing events he begins to question whether there is any truth to the myth of the Slender Man...