Nina Kautsalo, a Finnish policewoman, discovers two prostitutes dead and a third still fighting for her life during a regular check of an abandoned cabin in the isolated and snowy backcountry. The research takes an unexpected turn when an incredibly uncommon and lethal virus is identified in the blood of the surviving woman. Thomas Lorenz, a German virologist, is enlisted to help identify and contain the virus when the Finnish Bureau of Investigation takes over the investigation. Nina and Thomas must rely on one another in order to save their loved ones amidst the polar circle's infinite white expanse. However, what has precedence? A lethal virus or active serial killer?