Bogged down by the tedium of life in a small northern English town, Sarah Nelson desperately wants a change but seems unable to summon the motivation to make it happen. Following a chance meeting with Mathias, Sarah's life is propelled in a new direction. As she cautiously explores her feelings for Mathias, she begins to experience psychotic episodes, mental disturbances that she'd thought were left behind in her adolescence. Mathias sees in her distraught state an entirely unexpected possibility. A possibility that alarms Sarah even more than the episodes themselves. At the same time, near the English border with Scotland, a small team of detectives is presented with a spate of murders having similarities too significant to be coincidental. Inspector David Orbost and his partner Walter Pembroke struggle to unravel a knot that ties together the writings of a deeply religious woman born at the end of the sixteenth century, a decorated SAS soldier and a cult with only a handful of members in England held together by a charismatic but profoundly disturbed leader. As Sarah begins to suspect that Mathias is not the man he appears to be, her fate becomes entangled with David's investigation. Sarah is thrust into a situation for which nothing in her life could have prepared her. A situation and an ancient place of evil that will test her beyond her limits. Sarah finds herself in a fight against time, against fear and ultimately, against madness itself.