The historic Iron Curtain was located by Winston Churchill in eastern Europe, but the Gouzenko story and the Iron Curtain movie take place in Canada. Gouzenko is assigned to the Soviet embassy in Ottowa as a cipher clerk while World War II is still in progress and the USSR is Canada's ally against Nazi Germany. The film shows the Soviets already looking ahead to a resumption of the irrepressible class struggle. Embassy workers and Canadian communists are shown recruiting people (including a member of parliament) to spy on their government and military, and later on the atomic bomb program under way in the U.S. Gouzenko is a loyal communist initially, despite an early mis-step when he recites to his new boss his actual personal background instead of the fake details that have been prepared for him. Gouzenko is warned not to make friends with Canadians, but that's no problem until his wife (Gene Tierney) is sent over to live with him. She can't help trying to make friends with neighbors, especially after their son is born. Occasionally they take walks through the city, once stopping awkwardly outside a church as hymns play inside. It's hard to tell what we're supposed to make of their apparent distress. Does the churchiness of it all disturb them in some way, or do they recognize this as something inviting yet forbidden to them? Later in the picture, an older Soviet observes that he's old enough to know what truth is, or was, while Gouzenko's generation isn't so lucky. That seems to be the screenplay's dig at Soviet atheism, but what's really subversive for the Gouzenkos is the sheer fact of family life. It makes them start to think of having lives of their own, which isn't part, apparently, of the Soviet program.
Gouzenko is increasingly uncomfortable with the embassy's involvement in atomic spying. To him and his wife it all seems to promise a new war so soon after the victory over Germany. Igor (many actors pronounce it "Eager") is also troubled by the breakdown of a colleague grown guilty over his role in state terror. That unfortunate is duly shipped back to Moscow -- it's a damning fact that no one looks forward to being recalled to the old country -- and when Igor learns that his family is to return home after he trains a replacement, the Gouzenkos make a personal decision to defect and a moral decision to expose the atomic spy network. What follows apparently follows fairly closely the events of their actual defection, which fortunately fits the framework of a "they won't believe me" thriller. The Gouzenkos are spurned by government, law enforcement and media, none of the above taking them seriously. In a historically accurate yet thematically significant detail, only when the embassy staff invades the sanctity of the Gouzenko home, having discovered his theft of damning documents, do the police take action to protect the defectors. Governments and other institutions may not be reliable, but at least our society -- Canada for this purpose being effectively an extension of the U.S. -- respects property and family when totalitarianism doesn't.
Like other anti-communist films, Iron Curtain isn't really ideological if that word leads you to expect a defense of capitalism against communism. Communism is primarily a political threat, the tyranny over humanity of a conspiratorial, paranoid party. Curtain is less a polemical or patriotic film than a kind of film noir, and while cinematographer Charles G. Clarke didn't work much in that genre he makes an effectively noirish impression here. Unfortunately, Gouzenko's story doesn't give Andrews much to work with, and Tierney gets even less, and the postwar Fox gimmick of portentous pseudo-documentary narration distances the audience further from the characters. Wellman directs anonymously; it really could have been anyone behind the camera and for all I know the job was a loyalty test like I Married A Communist was at RKO. The music really is the most interesting thing about the picture; it so overwhelms the mostly uninspired proceedings that audiences might have wondered who really had the more interesting culture. More likely they just found the music too loud.