Winter has fallen on the South Pole. The sun will soon disappear for the next six months. A small team, known as the Winterers, will remain at the Polaris VI Antarctic Research Station to continue their innovative research, a crucial part in the fight against climate change, under the command of renowned biologist Arthur Wilde (John Lynch). But when spring comes, summer commander Johan Berg (Alexander Willaume) returns to the station only to find the entire team are either dead or missing. A killer is on the loose and Annika (Laura Bach), Johan's wife, is missing. If he wants to find her alive, he will have to trust Maggie (Katharine O'Donnelly), the young doctor who is profoundly shaken and apparently the sole survivor from the group - or, is there someone else?