Story opens in Switzerland in 1918 in the closing days of WW I and concerns Franck Villard, military attache to the Austrian delegation in Berne, and his French wife, Renee Saint-Cyr. Living in the neutral country has enabled the two to evade any claims which their two countries might make on their allegiances. Suddenly, Villard is asked to perform a hazardous mission aimed at putting in the hands of the French some highly secret (and bogus) Austrian military papers. Later, he appears to have been double-crossed by his superiors and is shot as a spy. His wife, furious, enlists as a spy for the Austrians and returns to France. Later in Vienna, as a highly successful Mati-Hari, she learns that her husband is not dead as reported but, by then, she is up to her neck in espionage.