The Next of Kin (d. Thorold Dickinson, 1942) was one of a number of wartime features - including The Foreman Went to France (d. Charles Frend, 1942), released, also by Ealing, the previous month - to warn of the dangers of careless talk.
The film concerns a supposedly secret British plot to attack a relatively unguarded German U-boat in occupied Northern France. But the element of surprise is lost thanks to a series of reckless comments by soldiers and civilians to, or within earshot of, German spies. Although the raid is ultimately a success, the British suffer very heavy losses. The Next of Kin is unusual for British propaganda films of the period in its willingness to portray British troops suffering near defeat. Churchill was reportedly appalled, and initially wanted the film banned as a threat to morale, before eventually being persuaded of the importance of its message.
The pre-title announcement begins, "This is the story of how YOU unwittingly worked for the enemy", and the film pulls no punches in communicating its message. Particularly chilling is a scene involving a young Dutch girl who is blackmailed into revealing secrets, and endangering her soldier sweetheart, by her Nazi employer. Realising the consequences of her actions, she stabs her tormentor to death, but is witnessed by a German spy, who strikes her down before turning on the gas to give her death the appearance of suicide. This cool brutality prefigures the even more powerful treatment of similar themes in Ealing's Went the Day Well? (d. Alberto Cavalcanti), released later the same year.
Originally commissioned as a military training film by the War Office, the film was expanded to feature length for general release at the behest of Ealing head Michael Balcon, who supplemented its modest budget of £20,000 with a further £50,000 from Ealing's coffers. Despite the film's box office success, however, the studio recouped its investment but no more; under the terms of the deal, all profits went to the War Office.