It’s Christmas on Gotland when the island is suddenly struck by an unspeakable tragedy — a high-school girl is found dead in the middle of a country road wearing a white Lucia gown. What at first appears to be an incomprehensible suicide soon proves to be something far more sinister, when behind the innocent facade it turns out that a group of girls at the local high school is harbouring dark secrets...

Two women, seemingly unconnected to each other, die in apparent suicides. But the strange circumstances cause Maria Wern and her colleagues at the Gotland Police Department to dig deeper, and soon the questions multiply. Was someone stalking the women? Is there reason to believe that they were suffering from some kind of psychosis? And is there a common denominator after all?

The charred body of a medium is found in the gutted remains of her office after a fire. And it soon turns out that she was murdered —suffocated with a plastic bag and doused in kerosene, the woman was left to die in the flames. When another two murders take place in the same manner, it becomes clear to the Gotland police that they have a serial killer on their hands - but without having the slightest idea what the victims had in common, or who the next one might be.

A ten-year-old boy disappears from a dinner in a little fishing village, while another vanishes from a refugee camp on the island. These are but the first in series of frightening events to take place on the island of Gotland, where a string of brutal murders are committed in quick succession. And what starts out as the search for a missing child, leads Maria Wern and her colleagues ever deeper into a nest of hidden agendas, personal betrayals — and links to international crime.

When Maria Wern of the Gotland Police Department receives anonymous death threats, she and her colleagues begin a frantic search to track down the source. Following a violent assassination attempt, however, she is ordered off the island for her own protection. Together with a group of old girlfriends from school, she secretly heads off to the pristine nature reserve of Stora Karlsö Island.