Charlie is approached by a man making mammoth claims while a young boy develops frostbite on a walk in the snow. Vincent makes a shocking discovery.
Vincent is taken to the police after his discovery and a woman mysteriously disappears. Sheriff Anderson tries to make sense of all the commotion as quietly as possible.
The search for Natalie Yelburton continues, while fingers get pointed towards Jason. Morton confides in Markus, a local teacher.
Dan and Frank go in search of a suspect, but Dan's feelings for Elena are threatening to overwhelm him; Morton uncovers a new piece of evidence.
Frank is taken in and interviewed by Morton, and after some thought, Elena reveals his alibi. Morton makes a disturbing find in Liam's room.
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.
Stanley Tucci
DCI Eugene Morton
Richard Dormer
Sheriff Dan Anderssen
Michael Gambon
Henry Tyson
Christopher Eccleston
Professor Stoddart
Darren Boyd
Markus Huseklepp