Based on the 1932 memoir I Was a Spy by Marthe Cnockaert, the film is about her experiences as a Belgian woman who nursed German soldiers during World War I while passing intelligence to the British.

In German-occupied Belgium in 1914, a local woman nurses injured German soldiers while passing information to the British.

Producer Michael Balcon sent Herbert Mason (who was initially production manager before becoming an assistant director) to take the script to Belgium and give it to Marthe Cnockaert to look at.

"[12] The Evening News (Rockhampton) (30 May 1934) praised the acting and described it as "[spectacular] in its sweep, human in its emotions, dramatic in its intensity and profoundly gripping in its appeal.

"[15] Adrian Turner for Radio Times said that, "Fans of vintage British cinema will enjoy this sprightly espionage yarn, set during the First World War and bearing a close resemblance to the Mata Hari legend.