British Intelligence.

During World War I, a master German spy has cost the British dearly. In desperation, they send for their best agent, currently undercover in Germany. Pilot Frank Bennett (Bruce Lester) is sent to pick him up, but the Germans are forewarned and he is shot down. While recovering in a hospital, Bennett is tended by a pretty nurse, Helene Von Lorbeer (Margaret Lindsay) turns out to be a spy herself. Posing as a refugee named Frances Hautry, she infiltrates the London household of Arthur Bennett (Holmes Herbert) and, coincidentally, Frank's father.