In the world of the film, the Ancient Ones require a specific narrative structure : the fool (the stoner) must be isolated, the whore must be punished, the virgin must survive last (or nearly last). The Index ensures that the is both effective and entertaining for the eldritch gods watching from below the Earth.

Zombie redneck torturers summoned by a diary.

The film follows a group of five college friends – Dana (Kristen Connolly), Jules (Anna Hutchison), Marty (Fran Kranz), Holden (Jesse Williams), and Wendy (Marie Avgeropoulos) – who embark on a weekend getaway to a remote cabin in the woods. Upon arrival, they discover that the cabin is equipped with an assortment of seemingly arcane objects and a mysterious supercomputer system. Unbeknownst to the group, their every move is being monitored and manipulated by a shadowy organization known as "The Facility," which has been using the cabin as a testing ground for an ancient ritual designed to appease the "Old Ones," malevolent deities from H.P. Lovecraftian lore.