During the dark days of World War II, a British traitor secretly gathers information for his Nazi overlords. Gleaning bits of news about military operations from careless, loose-lipped Englishmen, Davis relays them to his chief, who operates a London bookstore. When a Dutch refugee working at the shop, learns of their elaborate espionage activities, she is forced to cooperate or see her loved ones liquidated.

Originally planned as a simple propaganda piece of the “loose lips sink ships” variety, Next of Kin became an all-star vehicle that elicited good reviews from British critics despite its modest production values. Much of the film’s dramatic weight rests on the slender shoulders of former child star Nova Pilbeam, who had a key role in Alfred Hitchcock’s The Man Who Knew Too Much (1934) and shot to stardom as the leading lady in his 1937 thriller Young and Innocent. Newsreel footage from the front is adroitly blended with newly shot material. In keeping with the national willingness to participate in the war effort, many prominent actors, among them Jack Hawkins, Torin Thatcher, Basil Sydney, Phyllis Stanley, Basil Radford, and Naunton Wayne, take bit parts. When released in the United States, additional footage was shot as a prologue and epilogue, in which a General admonishes audiences to be tight-lipped.