"The Winter Over" by Matthew Iden

Each winter the crew at the Shackleton South Pole Research Facility faces nine months of isolation, round-the-clock darkness, and one of the most extreme climates on the planet. For thirty-something mechanical engineer Cass Jennings, Antarctica offers an opportunity to finally escape the guilt of her troubled past and to rebuild her life.

But the death of a colleague triggers a series of mysterious incidents that push Cass and the rest of the forty-four-person crew to the limits of their sanity and endurance. Confined and cut off from the outside world, will they work together or turn against one another? As the tension escalates, Cass must find the strength to survive not only a punishing landscape but also an unrelenting menace determined to destroy the station—and everyone in it.

Published 2017. Not part of a series.
I've read it and loved it.