Autumn 1915. The First World War is raging across Europe. Christopher Marlowe 'Kit' Cobb, a Chicago reporter and undercover agent for the US government, is in Paris when he meets an enigmatic nurse called Louise. Officially in the city for a story about American ambulance drivers, Cobb is grateful for the opportunity to get to know her. Soon his intelligence handler, James Polk Trask, extends his mission and he is active again. Parisians are meeting 'death by dynamite' in a new campaign of bombings, and the German-speaking Kit seems just the man to discover who is behind this.