Carl is trying to raise his blind son, Donnie, alone as best he can. After Donnie goes through a traumatic operation in an attempt to restore his sight, they return home to find something is seriously wrong with their world. For one thing, there is a hideous monstrosity awaiting Donnie in his bedroom cupboard and a red-eyed demon-woman stalking their every move as they flee their invaded home. Saved on the lonely roads of Aberdeenshire by a mysterious young woman who seems to know her stuff when it comes to the supernatural, they head off into the countryside to spend the night with Donnie's grandmother. But the evil follows, assaulting them with an increasingly bizarre array of terrible manifestations. And to add more terror to their plight, the long, cold night never seems to end.