Jessica Niemi is put on leave after a violent altercation between her and a belligerent man makes headlines. To escape the unwanted scrutiny, Jessica travels to a remote island in the Åland archipelago and rents a room at a small seaside inn. There she meets three elderly visitors who are the remaining “birds of spring,” former refugees who fled Finland as children during World War II and lived together for a few months in an orphanage on the island. The orphanage no longer exists, but the local legend about one of its inhabitants still haunts the surviving orphans. Every evening a girl named Maija would stand on the pier, but one night she disappeared and was never seen again. When one of the “birds of spring” is found dead, drowned alongside the same pier, Jessica tries to put the pieces of this terrifying mystery together.

Powerful executive Eliel Zetterborg has been found murdered in his upscale Helsinki home. What at first seems like a straightforward case soon proves to be anything but when it becomes clear the murderer has other targets. The only clue the police have is a photo of Zetterborg with three men whose faces have all been scratched off. Detective Jessica Niemi has taken some time off from her work with the Helsinki police to track down the coven that nearly killed her, and her partner, Yusuf, is assigned to lead the investigation. But as Yusuf delves into the case, he realizes he needs Jessica’s help. And as they dig deeper, they realize that the evil they’ve been hunting all along has returned and is lying in wait for the right moment to strike.

Six months have passed since investigator Jessica Niemi’s encounter with the mysterious serial-killing coven of witches and the death of her mentor. Now her homicide squad 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. 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 Jessica's mother and the witchcraft that undid her suddenly seem all too real, making Jessica wonder if the dead woman might be trying to tell her something about the killings.