On April 27, 1940, a Luftwaffe Heinkel He 111 bomber (1H+CT) finds itself under pursuit by a Fleet Air Arm Blackburn Skua (L2940) fighter near Grotli. Following the crash, three of the four German crew members survive: pilot Leutnant Horst Schopis (Florian Lukas), Feldwebel Wolfgang Strunk (Stig Henrik Hoff), and Obergefreiter Josef Schwartz (David Kross). Unfortunately, Unteroffizier Hauk does not make it. Although Josef suffers an injury to his arm, it seems manageable as they set out to reach the coast and rejoin the conflict.
As a sudden snowstorm hits, they lose their supplies and stumble upon a hunter's cabin. Inside, they discover two British airmen from another downed aircraft: Capt. Charles P. Davenport (Lachlan Nieboer) and gunner Robert Smith (Rupert Grint). The Germans make a calculated decision to allow them entry but keep them as prisoners of war. Horst establishes a divide in the room, warning the British not to cross it without permission. Their only source of sustenance, a limited amount of oatmeal, is shared equally, showcasing a semblance of fairness. Nevertheless, the tension is palpable, with Smith making his disdain for the Germans especially clear.
Struggling for warmth and comfort, they turn to dismantling parts of the cabin for firewood. Amid this, Horst takes Davenport's lighter, leading to a spirited protest from Davenport, who reveals it was a cherished gift from his father. Horst assures him it will be returned after their ordeal. With the weather worsening, attempts to seek help are futile, and they return to the cabin, their safety having been compromised by the tempest.
In a moment of desperation, Smith seizes Josef's weapon and aims it at his head, forcing the Germans to surrender their arms. The following day, he and Strunk go in search of food, hoping to spot some reindeer but only manage to catch a rabbit.
Back at the cabin, tensions escalate as Davenport instructs Horst to chop down a main support beam for firewood, a decision met with great reluctance. The cabin's structure begins to give in but is saved when both Horst and Davenport prop up the roof on small tables. Seizing the moment, Horst takes Davenport's gun, further complicating matters. As the confrontation heightens, both parties agree to a "cease fire", choosing cooperation as their best chance to survive. They secure all weapons in a box, and the atmosphere begins to shift as they bond over shared experiences, aided in part by Strunk discovering a hidden cache of supplies, which includes preserved meats and several bottles of alcohol.
As time passes, Josef's infection worsens, and the dire situation leads them to the drastic decision of amputating his arm for survival. The men, having forged an unexpected camaraderie, manage to get him intoxicated and undertake the painful procedure. They spend the night sharing stories of their lives, finding common ground amidst their shared struggle.
The following day, Smith and Strunk venture outside on skis to scout a potential escape route. Meanwhile, at a nearby military camp, a Norwegian scout has confirmed the location of the German aircraft. A small team is dispatched to investigate, and they encounter Smith and Strunk skiing back toward the cabin. In a tragic turn, Strunk is fatally shot by a Norwegian sniper, and Smith is captured.
Back at the military camp, a Norwegian officer interrogates the remaining British airmen, suspecting them of collaborating with the Germans. Horst unexpectedly walks in, returning Davenport's lighter, an act charged with unspoken emotions. As Davenport struggles to meet Horst's gaze, the Norwegian officer threatens harsh consequences, leading to Davenport's emotional outburst in defense of their actions aimed purely at survival.
The film concludes with Horst and Josef being taken away, presumably to a prisoner camp. In a reflective moment, Davenport and Smith approach the dock, exchanging a poignant glance with Horst. The epilogue reveals that both Horst and Josef end up as prisoners in Canada, while Davenport and Smith return to combat, leading to a tragic fate for Smith on their next mission.
In a final twist of fate, Davenport reaches out to Horst in 1977, inviting him to London, where these former adversaries reunite as friends, signaling the enduring bonds forged in the fires of adversity.
