"Based on fact, this carefullyreconstructed story of espionage in Belgium during World War One was one of thebiggest British films of its year, and from the peak period of its director,Victor Saville. Though more concerned with characterization and suspense thanwith spectacular action, it holds interest throughout and is an unusuallyhandsome production (with a) strong cast."-William K. Everson Madeleine Carroll portrays the Belgian nurse Marthe Cnockhaert, whospied for the Allies and attempted to blow up an arms dump to prevent a Germangas attack.