1) The narrator, Lauren, receives a strange letter from her sister Kate asking her to come to Oakside. When Lauren arrives at Kate's house, Kate is missing. Lauren finds odd notes and instructions left around the house.
2) The story is based on documents found in the woods near Oakside and may provide clues about what happened to Kate, Lauren, and Kate's son Charles who have been missing for 3 months.
3) As Lauren searches for Kate in the woods, she encounters a strange creature and finds more unsettling notes. It seems Kate and someone named C.R. knew about the creature, known as Slenderman, and were trying to