When Admiral Seville (Michael Rennie) was still just Lt. Seville, he had a brief affair with Canadian beauty Lucinda (Wendy Hiller) and, unbeknownst to him, fathered a son. Now, twenty years later, that boy (nicknamed Canada) serves in his father's command, neither one knowing the truth about their relationship. While tracking a German raider, Sevilles ship is torpedoed and while some escape in lifeboats, Canada (Jeffrey Hunter) is taken prisoner. Damaged in the exchange as well, the German ship pulls into a well-hidden cove to affect some repairs. Canada takes the opportunity to escape, and after arming himself, he flees into the hills to conduct a guerilla war, hoping to slow the enemy's progress down long enough for reinforcements and rescuers to arrive.