Jan Balsrud, a Norwegian soldier sent on a mission to German-occupied Norway, was the protagonist in 1943 of a dramatic adventure together with other comrades. The group was discovered by the Germans who killed all of Jan's companions. He, wounded in the foot, managed to escape by facing a very long march in the mountains, to make him lose track. He suffers cold, hunger and is struck by blindness due to the glare of the snow; he finds the strength to amputate his sick toes to stop the gangrene. His compatriots find him and carry him to the rescue. The film was shot with the advice of Jan, the survivor of the terrible adventure.