On the day that their parents die, sisters Lilly and Victoria vanish in the woods, prompting a frantic search by their Uncle Lucas (Nikolaj Coster-Waldau) and his girlfriend, Annabel (Jessica Chastain). Five years later, miraculously, the girls are found alive in a decaying cabin, and Lucas and Annabel welcome them into their home. But as Annabel tries to reintroduce the children to a normal life, she finds that someone – or something – still wants to tuck them in at night.