Southern Sweden: Beautiful countryside, endless forests, coastal walks, dark days - and even darker nights. But beneath the beauty lies a dark heart... Skåne, 1986: On the night of Walpurgis, the eve of May Day, where bonfires are lit to ward off evil spirits and preparations are made to celebrate the renewal of spring, a sixteen-year-old girl is ritualistically murdered in the woods beside a castle. Her stepbrother is convicted of the terrible deed and shortly after, the entire family vanishes without a trace.

Trying to process a life crisis Gothenburg policeman, Dennis Wilhelmson, decides to take a trip to his quiet childhood island, Smögen.

Detective Inspector Karen Eiken Hornby has returned to the main island, Heimö, after many years in London and has worked hard to become one of the few female police officers in Doggerland. So, when she wakes up in a hotel room next to her boss, Jounas Smeed, she knows she's made a big mistake. But things are about to get worse: later that day, Jounas's ex-wife is found brutally murdered. And Karen is the only one who can give him an alibi.

When a body of a woman is discovered at a lighthouse in the Icelandic town of Akranes, it soon becomes clear that she’s no stranger to the area. Chief Investigating Officer Elma, who has returned to Akranes following a failed relationship, and her collegues Sævar and Hörður commence an uneasy investigation which uncovers a shocking secret in the dead woman’s past that continues to reverberate in the present day.

On the day Stockholm police officer Hanna Ahlander’s personal and professional lives crash, she takes refuge at her sister’s lodge in the Swedish ski resort paradise of Åre. But it’s a brief comfort. The entire village is shaken by the sudden vanishing of a local teenage girl. Hanna can’t help but investigate, and while searching for the missing person, she lands a job with the local police department. There she joins forces with Detective Inspector Daniel Lindskog, who has been tasked with finding the girl. Their only lead: a scarf in the snow.