In late March 1943 25-year-old Norwegian commando Jan Baalsrud, three other Special Operations Executive officers and a crew of eight sailed northeast from the Shetland Islands aboard the fishing boat Brattholm. The four-man team was to recruit resistance members in far northern Norway with an eye toward sabotaging enemy installations. Their jumping-off point was an island north of Tromsö, Norway, 270 miles above the Arctic Circle. The mission soon went awry when Baalsrud and companions revealed themselves to a shopkeeper they mistakenly believed to be their contact. Fearing he was being tested by the Germans, the man alerted authorities to...