Overgård, portrayed by Mads Mikkelsen, finds himself isolated in the unforgiving Arctic Circle, trapped within the wreckage of his plane while he eagerly awaits rescue. His existence has dwindled to a monotonous routine: tending to fishing lines, meticulously mapping his barren surroundings, and operating a hand-crank dynamo to send out a distress beacon at the same time each day from a nearby peak. To signal for help, he has painstakingly carved a large "SOS" sign in the snow near his downed aircraft. Having already suffered frostbite and lost a couple of toes to the extreme cold, his situation grows increasingly dire.
One fateful day, a polar bear invades his precious stash of fish, which he has been struggling to catch through ice fishing in icy waters. Just when hope seems dim, a helicopter responds to his distress signal. However, as it attempts to land amidst a violent ice storm, it tragically crashes. The pilot, played by Tintrinai Thikhasuk, loses his life in the ordeal, while the sole passenger, Maria Thelma Smáradóttir, is left severely injured and unconscious.
Determined to save her, Overgård tends to her wounds, ingeniously using staplers to close a deep gash in her abdomen, and transports her to his plane using a sled crafted from the helicopter door. Despite the language barrier, with her being a Thai national who speaks no English, she shows signs of life by squeezing his hand. Overgård returns to the wreckage of the helicopter to search for supplies. He buries the pilot and uncovers food, a propane cooking stove, medical gear, a sled hidden away, and a map of the area that indicates the nearest safe haven—far from reach.
Despite the woman's critical condition worsening and the antibiotics running low, Overgård resolves to embark on a perilous journey to the seasonal refuge marked on the map, dragging her in the sled behind him. After three grueling days, he arrives at a flag position he had set up earlier, at the edge of his previous explorations. However, he encounters an unmarked steep slope on the map and despite multiple failed attempts to hoist her upward using ropes, he is forced to take a longer and more treacherous route, knowing that this decision will delay their rescue by several days.
Their arduous trek leads them to take shelter in a cave one night, only to be confronted by yet another polar bear lured by the smell of their cooking fish. Utilizing a distress flare, he successfully fends off the bear, but the following day sees the woman’s deteriorating condition and his own fingers beginning to suffer frostbite. In a moment of despair, believing she may be dead or slipping away, he sadly leaves her behind to continue alone, ensuring she has the cherished photo of her family tucked away with her.
As fate would have it, he soon finds himself falling into a crevasse, knocking himself unconscious. Regaining consciousness, he finds one of his legs trapped under a boulder. Struggling against pain and injury, he finally frees himself and makes his way back to the woman's sled, where he discovers to his relief that she is still alive. Overwhelmed with guilt, he resolves to continue their treacherous journey together, despite his leg's injuries.
Just when Overgård feels he is nearing the end of his strength, he spots a helicopter in the distance. With a dwindling flare supply, he desperately tries to signal the crew, even lighting his parka on fire in hopes of attracting their attention. Alas, the helicopter takes off, leaving him feeling defeated as he lies next to the woman, holding her hand and preparing himself for what seems like the end. But in a twist of fate, as he closes his eyes, the helicopter unexpectedly lands behind them, signaling a glimmer of hope amidst their harrowing ordeal.
