Caught under the tyrannical thumb of her new prioress, Dame Frevisse finds welcome relief in leaving St Frideswide nunnery on a pilgrimage. But the road brings with it unwelcome company: the wealthy Lionel Knyvet has been possessed by a foul demon. Seeking relief from the horrific terrors visited upon his body each fortnight, Lionel has dragged his entire household on an endless pilgrimage across the length and breadth of England. Frevisse wants nothing more than the peaceful bliss of travel, but must instead endure the incessant chattering of a mob. Lionel's possession, however, may only mask a darker sin. When the pilgrims make their way to the manor house at Minster Lovell, Frevisse begins to unwind the bitter poisons of jealousy and betrayal eating at the hearts of both Lionel and his brother Giles. Against her will, the innocent nun is drawn into the vilest depths of the human soul and there she unlocks the mysteries of a blackened heart. But even when the truth comes out, can justice be done? The pure of heart will find no peace when murder and death come knocking at the manor's door...