Finnish police Nina Kautsalo makes a horrific discovery in the basement of wilderness cabin. Soon the find brings German virologist, Thomas Lorenz, to work on the case.

Raunola, the man suspected for the murders is leaving the investigators confused. The virus investigation takes a bad turn, and Nina and Thomas find each other in surprising place.

Nina and Thomas are in danger when Raunola returns to Ivalo. Marita gets bad news in quarantine.

Nina and Thomas get new information from a surprising source. Thomas has to fight for his daughter's custody. Virus infection takes a frightening turn.

Nina and Thomas return to Finland. Venla gets help from unexpected source. Nina will have to step into the darkness once more.