BALTIMORE - In 1942, the Gestapo circulated posters offering a reward for the capture of "the woman with a limp. She is the most dangerous of all Allied spies and we must find and destroy her." The dangerous woman was Virginia Hall, a Baltimore native working in France for British intelligence, and the limp was the result of an artificial leg. Her left leg had been amputated below the knee about a decade earlier after she stumbled and blasted her foot with a shotgun while hunting in Turkey. The injury derailed Hall's dream of becoming a Foreign Service officer because...