The script is about a 10-year-old boy named Oliver Brown who begins meeting manifestations of his fears at night, including Nycto (fear of darkness), Maze (fear of being lost), and Acro (fear of heights). At first, the encounters seem friendly, but the monsters grow more sinister and dangerous over time. The story follows Oliver living in an upper-middle class English home with his parents as he struggles with the trauma of the nightly visits. In the climactic final night, Oliver fights most of the monsters but is ultimately overpowered by Nycto and killed.