Six months have passed since Jessica's encounter with the mysterious serial-killing coven of witches and the death of her mentor. Her nightmares about her mother and the witchcraft that undid her have only gotten worse, but she's doing what she can to stay focused. Her homicide squad, now under new leadership, has been given a murder case and a new series of disappearances to investigate. A young woman's corpse has washed up on an icy beach, and two famous Instagram influencers have gone missing at the same time.

The missing influencers and the murdered woman all have ties to a sinister cult. Jessica finds an eerie painting--of a lighthouse on a remote island--as she investigates, and under the picture is a gruesome poem detailing a murder. The nightmares about her mother suddenly seem all too real, making Jessica wonder if the dead woman might be trying to tell her something about the killings. And as Jessica works frantically to solve her latest case, her horrific past comes roaring back and threatens to destroy her.