Harper Ashbury is walking through the Shambles when she bumps into a ghostwalker, a man giving ghost tours, and has a visceral vision of his death. She doesn’t know how to interpret the sensations she experiences so continues with her day, shocked but not concerned. When his body is found the next day, she is guilt-ridden. Harper researches the gruesome murder, using her job as an archivist in the cathedral’s secret vaults to access illegal documents. The archbishop then orders Harper and her foster-sister, Grace De Santos, to investigate as Grace’s family are demonhunters. The two women go to the place where the ghostwalker was murdered and Harper has a vision of his death. They’re interrupted by Saqib Siddique, a forensic supernaturalist. Harper feels his skills could be useful and promises to keep in touch. That night, Harper has a nightmare about a forest of eyes. She doesn’t know it yet, but this relates to her past as she can’t remember anything from before she was thirteen when Grace’s father found her wandering in the mists of Swaledale. Feeling weary and scared, Harper tries to emulate a historical scryer and gain control over her visions. Instead, she accidentally summons a demon, Heresy. He tells Harper something is hunting her through her dreams and promises to teach her magic and conceal her in exchange for letting him stay. When Harper reaches the cathedral the next day, the archbishop tells her that the deacon of the cathedral has been murdered. Saqib is already examining the body and has dis-covered both corpses are missing organs and have mysterious runes carved around the wounds. While attempting to scry for the killer, Harper discovers the location of the next murder but finds it cordoned off by police tape when she arrives. Saqib examines the body and finds the same runes. Because all three victims are missing body parts relating to speech (vocal cords, lips, tongue), Harper believes someone is trying to silence people. The arch-bishop confirms her suspicions when he tells her that the deacon left him a voicemail just before he died stating he found something at the ghostwalker’s guild house. Grace and Harper break into the guild house but are caught. The two women speak to the guild master who reveals that these murders have happened before but won’t give de-tails. Heresy slips away and infiltrates the ghostwalkers’ computer. He finds evidence files have been removed from the computer by magic. He follows the trail but is captured. Harper experiences another vision of the forest of eyes and finds a corpse in a tree at the end of it. She recognises the location and sprints there, both afraid and hopeful of catching the killer. She encounters a supernatural creature but is unable to restrain them and they escape. Harper is sickened to find the body of a young woman whose eyes have been gauged out. The Queen’s Guard arrest Harper but release her when the archbishop intervenes. Heresy returns after Harper has a vision of her past, reiterating that something is chasing her through her dreams. He has discovered the murder the guild master mentioned was a woman whose body parts had been sold at auction. He and Harper search online and find a similar auction. Harper, Grace, Saqib, and Heresy go to stop it. Harper is taunted by the auctioneer who tries to convince her to sell her eyes. Ze tells her that the body parts from the York murders were not taken to be sold but were taken by an ancient British supernatural. Harper fights the Auctioneer and escapes but fails to rescue zir prisoners which galvanises her desire to protect both humans and supernaturals. Harper has a vision of a Viking village and realises the next murder will take place at a local attraction which has a replica village as its centrepiece. She meets the killer at the attraction and discovers it’s the spirit of the River Ouse. The river escapes after claiming another victim. Doing research in the cathedral archives, Harper learns of a spell called The Hiding that stops humans being able to perceive supernaturals. The runes in the spell match those on the victims. On her way home, she’s stopped by a techno-witch, AJ Tailor, who has been sent by his coven to kill her. She accuses him and the coven of selfishness because they knew what was happening and did nothing to help either humans or supernaturals. AJ has a change of heart and joins Harper’s team. Harper and her friends catch the killer using a magical entrapment circle and Saqib’s prototype device for detecting magic. Talking to the Ouse, Harper can tell the river is reluctant to murder people but feels duty-bound to complete the Hiding. The spell to trap the Ouse seems to go wrong, freezing the river who then shatters.