Katie Jensen (Annalise Basso
) is one of a group of four high school girls who are longtime friends. They live in the small town of Winsford, Massachusetts and although the other three girls are more or less happy with their lives, Katie tells them she wishes they were older so they could all get out of the town, which she despises.
Shortly after, Katie goes missing. The police launch a search and put up missing posters. The girls go through Katie's computer and find the last site she visited before disappearing is about an entity named Slender Man, who preys on innocent youth. They search the site for clues about how to find Katie, and venture into the woods to find him, but soon discover Slender Man is haunting them.
, Julia Goldani-Telles, Jaz Sinclair, Annalise Basso
, Alex Fitzalan, Taylor Richardson, Javier Botet