From 1984 to 1998, 15 Child Abductions and supernatural happenings were reported. Detective Bruce Fletcher was determined to find out who was behind the disappearances but suddenly cut himself off from all contact for 6 months and was found dead from a heart attack. His Son, Brian continues to carry on the work for him. Brian begins to notice a Tall Man in several images of the abducted children, but others ignore his concern.
After dropping his son, Jake and 6 others off at a forest where they had planned a camping trip, Brian visits a mother of an Abducted Girl. He learns that the girl drew pictures of her and a tall ‘Imaginary Friend’ hand and hand, outside a forest. The man had no facial features, a tuxedo and long arms. Brian begins to show concern for his daughter, Emily, who has been showing signs of whispering to herself.
Later that night, The Detective dreams about a tall, skeletal figure with long arms kidnapping Children in Ancient Greece. The same night, strange happenings begin to occur among Jake and his friends, Jake thinks it a good idea to film the events. Brian's historian friend tells him of an Ancient Greek god named Lepto (Slender), who took children from their families and slaughtered them before they died a painful death. After 2 of Jake's friends go missing they split up and start a Search Party, while on the other side of the city, Detective Brian Fletcher may have found the reason his father was locked away for 6 months.