During World War 2, a stranded German U-boat crew, ashore in the hostile wilds of Canada, must make it to the safety of the United States border without being captured. If you find yourself yelling, "hold on a minute!" keep in mind that the film takes place in 1941 and was released mere months before the US entered the war. Before that, although the US had been supporting the Allies in their war efforts, their official position was one of neutrality, so if the crewmembers made it across the 49th parallel—"a line drawn by men upon a map nearly a century ago, accepted by a handshake and kept ever since" according to an opening voiceover—US officials were bound by duty to return them to German hands.

That such a film, featuring humanized Nazi protagonists, could be released in the midst of war is a marvel; that the film, cut by 16 minutes and retitled The Invaders, could be nominated for Best Picture the next year was even more outrageous. Hollywood at the time was pouring out dozens of propaganda films in which the Nazi enemies were little more than savages. The seemingly subversive technique of humanizing the enemy, instead of working against the loudly propagandistic nature of the film, serves instead to ratchet up anti-Nazi sentiment. It starts out with a homogenous group of textbook Nazis, and then, as the crew slowly make their way across Canada, it humanizes some of them, showing how regular people could get caught up in Hitler's grand plan. But Powell and Pressburger turn things around by slowly eliminating the humanized characters, revealing another, more complex side of the Nazi horror by showing that there's no room for humanity in its ranks. It's an extremely effective technique, and it makes for an extremely effective film.

U-boat 37 has been terrorizing Canadian shipping in Hudson Bay for months. Right after its captain sends a small crew to shore to steal provisions and perhaps claim a little bit of Canada for Germany, the U-boat is sunk, leaving the six sailors trapped in Canada. As they make their way across the vast continent, they encounter a wide variety of quirky Canadians: an apolitical French-Canadian trapper (Laurence Olivier) who gives his life in an attempt to alert the rest of the country to the Nazis' presence; a Hutterite outpost full of German refugees from Hitler's pogroms; a pacifist naturalist and historian (Leslie Howard) whose remoteness from the events of the world enrages the Nazis; and an AWOL Canadian soldier (Raymond Massey) who, despite his complaints about his service, is still willing to fight for his country. In each sequence, the Nazis, confident that their way of life will be attractive to the malcontents and observers they encounter, find that their audience believes that Canada's liberal democracy is infinitely better than fascism.

The "star" of the film is Eric Portman, who plays Lt. Hirth, the eventual leader of the crew, but the film and its promotional materials trumpet the presence of Sir Laurence Olivier and Leslie Howard above Portman. Hirth is the prototypical Nazi; it is his fanaticism that propels the crew toward the American border. He believes, rightly, that the entire world is watching them: if they can face off against 11 million Canadians and succeed, it will be an invaluable propaganda tool for the Nazis. He's blinded by his fanaticism, though; he thinks that his example is enough to convince the Canadian misfits he meets that they should support the Nazis. He finds himself rejected again and again, first by the Canadians, and eventually by some of the surviving members of his crew. The most humanized Nazi is Vogel (Niall MacGinnis), a gentle young man who was a baker in his former life. He's attracted by the Hutterites' way of life, and, after discussing with the Hutterite leader, Peter (Anton Walbrook), how he found himself in a Nazi uniform, and after falling in love with Anna (Glynis Johns), whose parents were killed by Nazis, he decides to desert his crew and stay on. The film's biggest emotional punch comes when Hirth deals with Vogel's disloyalty.

The propaganda elements are interesting as well, mainly because they're handled through conversation, not through violence. The most fascinating parts of the film come when Hirth and his crew engage in dialogue with Canadians, from the apolitical (Olivier) to the pacifist (Howard) to the patriotic but disillusioned (Massey). Emeric Pressburger and Rodney Ackland's intelligent screenplay provides some of the most reasoned and elegant defenses of liberal democracy in mainstream film. Sometimes it comes in well-thought monologues, and sometimes it feels fresh, like when Massey, who is almost/sort of/not quite a deserter, tells Hirth that "We own the right to be fed up with anything we damn please and say so out loud when we feel like it!"

My favorite, if somewhat improbable, scene comes after the remaining Nazis have tied up Philip Armstrong Scott (Howard), burned his manuscripts and paintings, and stolen his clothes and gun, after berating him for being a coward for not joining the army. Scott does a quick self-analysis, decides that he's not in fact a coward, and sets off determinedly to punish the Nazis for being bad-mannered and for being bad shots. In a sad epilogue to this film, Howard, who served as a British spy, was killed in 1943 when his plane was shot down by the Luftwaffe.

The film is full of gentle and not-so-gentle nudges at the United States. It would have been galling to remind the sleeping giant that its neutrality provided for the safety of marauding killers; it's probably not an accident that its US release was delayed until the winter after the US entered the war. It was incredibly well received—it was the highest grossing British movie in American history at the time, and it was honored with three Oscar nominations at the 1942 awards: Picture, Screenplay, and Original Story, the latter of which it won.