1974, Oxford. Detective Briony Williams, starting a new job with the Thames Valley police in Oxford, is called to investigate the murder of a 17-year-old girl. Convinced that the girl’s murder is no ordinary domestic crime, Briony delves into the world of the supernatural when she finds a stone carved with an ancient cryptic message clutched in the victim’s hand. The police need solid scientific evidence that will stand up in court, but in order to solve the case Briony must ally herself with a psychic girl and a druid leader. As she investigates, the danger deepens, setting her directly in the path of a killer bent on eliminating anyone getting close to the truth. Undeterred, Briony must steer a course between the rational and the supernatural in her search for The Visitor.