In the remote Arctic town of Fortitude, two children make a remarkable find, while the discovery of a horrific crime brings a new arrival to the island that complicates Sheriff Dan Anderssen’s investigation.
Dan and Frank go in search of a suspect; however, Dan's feelings for Elena are threatening to overwhelm him. Morton, meanwhile, uncovers a new piece of evidence.
Shock waves reverberate around Fortitude as the killer is revealed, while Morton tunes his attention to the death of a scientist on the island months earlier.
While Morton uncovers new information about the death of Billy Pettigrew, Hildur makes a heart-breaking discovery. Another gruesome event occurs in Fortitude.
Panic sweeps through Fortitude as news of the second attack spreads. Dan and Morton must work together while Frank hopes the latest events will exonerate Liam.
DCI Morton pursues Henry Tyson into the Arctic wilderness in search of the truth, while worrying test results force Governor Odegard to take drastic action.
In the penultimate episode, the truth about Billy Pettigrew is revealed. In the lab, Natalie and Vincent probe the cause of the disturbing events in Fortitude.
The chilling thriller concludes with a dramatic and emotional finale. Vincent faces a life-threatening situation, while Dan must make a devastating decision.
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.
Oslo sends two new officers to attempt to make some sense of the anarchy in Fortitude. Dan Anderssen continues his descent into madness, bringing him face to face with a grief-stricken Michael Lennox.