Disgraced investigative journalist Maya Lin has one shot at redemption: a black box proving Grant Omnicorp is weaponising the weather. Her escape route is the Northern Star Express, speeding through the Montana wilderness on Christmas Eve. But she isn't the only one with secrets. Dr Carter Grant, the estranged son of the technocrat she's hunting, is onboard to save a dying child. When the temperature outside plunges to an impossible -40 degrees Fahrenheit, the train is derailed by an artificial blizzard designed to kill them. Trapped in the wreckage and hunted by an elite ghost unit of assassins, Maya and Carter must put aside their differences and survive the freezing cold with the killers closing in.