When offered the post once styled 'diocesan exorcist', the Revd Merrily Watkins - parish priest and single parent - cannot easily refuse. But the retiring exorcist, strongly objecting to women priests, not only refuses to help Merrily but ensures that she's soon exposed to the job at its most terrifying.

And things get no easier. As an early winter slices through the old city of Hereford, a body is found in the River Wye, an ancient church is desecrated, and there are signs of dark ritual on a hill overlooking the city. Meanwhile, reports of psychic unrest in the Cathedral itself - where the famous shrine of St Thomas Cantilupe lies in fragments - reflect an undying evil lying close to the heart of the Church itself.