"Tunn is" translates to "Tunn is" in English.

Swedish Foreign Minister Elsa Engström travels to Greenland to push through a ban on oil drilling in the Arctic. Suddenly, her advisor Viktor is taken hostage during an elaborate attack on a nearby ship.

Liv is forced to take matters into her own hands when she is denied participation in the investigation into the ship attack. Elsa tries to convince her ministerial colleagues to continue the meeting. Local police chief Enok discovers a…

Tasiilaq is cut off from the outside world as a result of sabotage. Enok is suspected of crimes while Liv discovers a connection between the ship's attackers and the Russian government (which actively opposed Elsa's deal).

Liv and Enok begin to work together. They travel north to follow up on a clue that may lead to the kidnapped crew. Elsa's proposal loses support among the other ministers when she is subjected to a smear campaign from the Russian side.

The ship's owner, Ville Berger, travels to Tasiilaq to offer support to the crew's families. Life collapses under the psychological stress and Elsa struggles with several setbacks that together lead to a life-changing decision.

Elsa responds with a bold countermovement when she becomes the target of blackmail. The council crumbles and Elsa finally looks like she's getting the support she needs. Liv and Enok discover a new trail and choose to defy all regulations…

Ville Berger is awarded rights to drill in the Greenlandic oil well and Sweden's relations with Russia deteriorate further when new theories emerge. At the same time, Liv and Enok are faced with a brutal showdown in the cold wasteland.

Long-awaited reunions await in Tasiilaq, but Enok's family is still missing and Liv decides to help him. Elsa is determined to get her contract signed when an unexpected offer changes everything.