It begins in the fog, with a bleak village funeral. In the early hours of the following morning, Merrily Watkins and her daughter Jane are made aware that Aidan Lloyd, son of a wealthy farmer, will not be resting in peace. A rural tradition is displaying its sinister side as an old feud re-ignites. It's already a fraught time for Merrily, her future threatened by a bishop committed to restricting her role as deliverance consultant, or diocesan exorcist. Suddenly there are events she can't talk about as she and Jane find themselves potentially on the wrong side of the law. Meanwhile, DI Frannie Bliss, investigating a shooting, must confront the growth organized crime which is contaminating the countryside. On the Welsh border, the old ways are at war with the modern world. As the days shorten and the fog gives way to ice and snow, Merrily Watkins is drawn into a conflict centered on one of Britain's most famous medieval churches, its walls laden with ancient symbolism.