In Blackthorn Hollow, Maine, writer Elliot Crane rents a remote cabin to salvage his failing novel, but the house hides a secret: a fifth room, not listed, only accessible at midnight. Behind its wall lies a perfect replica of his city apartment, where another Elliot—sharper, bolder—writes the masterpiece he can’t. As the mirror in the room reveals a smiling doppelgänger, Elliot’s reality unravels, his words stolen, his mind fraying. The Hollow beneath the cabin hungers for more than his talent—it wants him.