Winter has fallen on the South Pole. 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. After the winter, Johan Berg returns to base, finding most of the team dead or missing. Only Maggie remained at the station.

The summer team tries to find clues of what could have happened during the winter, unveiling a first possible suspect.

Arthur reveals that the body found by the team was that of Sarah Jackson's. Meanwhile, Maggie discloses that Sarah's death was not an accident. She was murdered.

Jolted by the revelation of Sarah's death, Maggie reveals that the killer was looking for something which Maggie found and kept with her.

In the middle of the winter, a small group of scientists in charge of an international base in the Antartica during the long polar nights stops communicating with the outside world.