Wim Hof, the Dutch adventurer known for enduring extreme cold, sets out to run a full 26-mile marathon above the Arctic Circle wearing only shorts and sandals, with temperatures well below freezing. The film follows the preparation and the run itself, tracking his breathing techniques and cold-exposure training, the methods behind nine previous world records for enduring cold, including barefoot marathons and prolonged ice-water immersion. Physiologists and observers on the ground weigh in on what his body is doing that theirs cannot, while the camera stays close on his face and feet as the miles wear on and the temperature drops further. The Arctic terrain itself becomes an obstacle as much as the cold, with wind and snow slowing his pace. The film treats Hof's claims about controlling the body's response to cold as a real physiological question, using this marathon as the test case rather than simply celebrating the stunt.