Governor Odegard is presented with devastating news as Sheriff Dan struggles for his life, and a new threat makes its presence known.

Natalie and Vincent head out into the wilderness and the police track down their suspect, but a dark turn of events leads them to question everything.

Eric struggles to keep control as the body count increases. Meanwhile, Natalie and Vincent's field trip descends into chaos.

A disturbing challenge is issued. Michael finds a glimmer of hope for Freya, while Vincent's trust in Natalie is shattered.

Dr Khatri attempts to cover her tracks when Michael presents the scientists with a miracle. Dan and Elena relive their trauma.

Michael finds something unexpected on the tundra, and Dan is confronted with what he is becoming, just as a heartbreaking discovery changes the town forever.

As the town attempts to come to terms with the recent tragedy, Petra and Ingrid seek the truth. Meanwhile, Dr Khatri moves a step closer to achieving her goal.

Dan faces his toughest battle yet as someone makes the ultimate sacrifice for the greater good, while Michael and Ingrid venture out in search of justice.

The people of Fortitude take matters into their own hands. Dan seeks his own vengeance, but is there still a demon among the herd?