The Captive Heart is set in a World War II prisoner of war camp, but its theme stretches more broadly than the usual prisoner of war camp film. It isn't about enduring the hardships of the camp, nor about elaborate escape plots, although both of these subjects are briefly touched upon. No, The Captive Heart is a study of how human beings cope with being physically imprisoned while their hearts and emotions remain unrestrained.

Each of the central characters has a personal story, and these are where the heart of the film resides, rather than in any central plot. Each man has a matter more immediately pressing to him than the war. All of them are at least imprisoned by the Germans, but some are imprisoned in other ways as well, such as one young man who may or may not recover his sight. The most compelling story involves a man who has imprisoned himself in order to survive. Circumstances forced him to take on a false identity, and then, tragically, force him to keep up the masquerade even when it means returning letters to a dead man's wife.

This is a British film. The British have long had an understanding of how to use subtlety to drive home messages that are less convincing when overstated. The subject matter in The Captive Heart is weighty, but the film understands that weighty matters of the human heart are things everyone bears every day: prisoners of war merely deal with theirs under more extreme conditions. So it avoids pushing the audience too hard to embrace these characters and their passions and worries. Instead, it simply sets about telling their stories as plainly and earnestly as it can. The success of the approach is unquestionable: gradually, we are drawn into their stories, and by the time things are wrapping up, we may be surprised at how involved we have become.