In December 1942, two young soldiers abandon their posts at checkpoint 83 in North Värmland, Sweden, venturing into the frigid winter night towards the Nazi-occupied Norwegian border. With Sweden teetering on the edge of invasion, they are eager to confront the enemy everyone is discussing. However, their adventure quickly turns disastrous, and Lieutenant Aron Stenström soon learns that his brother Sven is among the missing soldiers. Facing overwhelming odds, Aron embarks on a covert rescue mission behind enemy lines. As he navigates the dense Norwegian forests, Aron discovers that a different kind of boundary must be crossed if they are to survive.