Over the Rhine : the world's greatest spy story

Cover title: Over the Rhine, an expose of the Kaiser's spy system.
Title continues: A thrilling story of an American college boy, who in the disguise of a beautiful woman wormed his way to the heart of the Kaiser's court and with the cunning that matched American brains and skill against German Kultur and intrigue, sprung the fatal trap that blotted from existence the Kaiser's master spy.
Also available in digital form.