Kyle can barely remember his grandfather. So when they inherit his old house – a damp, secluded tower on the edge of a Welsh mountain village – Kyle and his wife, Lydia, feel they are moving into the home of a stranger. From the start, Lydia hates the house: the disturbing paintings in the attic, the hostility of the locals, the peculiar light that pours through the kitchen window. Kyle thinks Lydia needs a break from London, from the nightmares and the panic attacks. But over the coming weeks, Lydia’s sense of dread only becomes more insistent, whilst Kyle is drawn to the house in ways he cannot explain. Yet as winter approaches, cutting them off, the house must become their refuge. For outside, on the mountain, something is calling to them. Something that has waited decades, and wants to be let in.