When Billy, a troubled young man, comes to private eye Cormoran Strike's office to ask for his help investigating a crime he thinks he witnessed as a child, Strike is left deeply unsettled. But before Strike can question him further, Billy bolts from his office in a panic. Trying to get to the bottom of Billy's story, Strike and Robin Ellacott set off on a twisting trail that leads them through the backstreets of London, into a secretive inner sanctum within Parliament, and to a beautiful but sinister manor house deep in the countryside.