Early in World War II, ''German submarine U-37 (1938)'', a German U-boat, makes its way to Canadian waters and participates in fictional anti-shipping activities similar to those of the later Battle of the St. Lawrence. The U-boat evades the Royal Canadian Navy and Royal Canadian Air Force patrols by moving north. A raiding party of six Kriegsmarine sailors are put ashore to obtain supplies but soon after, the U-boat is sunk in Hudson Bay by RCAF bombers. The six attempt to evade capture by travelling across Canada to reach the neutral United States and return to Germany.