Fraught economic pressures force Adam Hitchens, a London based conservationist, to take a job surveying an Irish forest. He hopes the move to a millhouse deep in the idyllic countryside will be a breath of fresh air for his wife Clare, their young baby son Finn and dog Iggy. Not everyone approves of their arrival however. A farmer with strong beliefs in local tradition and folklore warns of danger if Adam does not stop unsettling the ancient, sacred forests with his tests and assessments. When someone or something breaks into the house at night with the apparent intention of harming their child, the worried couple believes the locals are taking it a step further, intent on driving them away. But after the police aren't able to catch the elusive intruders, events take a turn for the unexplainable and terrifying when the millhouse comes under attack.