Count Richárd Eszterházy, one of the most cunning spies of the Austro-Hungarian Empire, is entrusted with a mission of a particular importance: he has to discover the military secrets the Head of the Imperial-Royal Intelligence has sold to the most dangerous enemy of the Empire. István Ritter, a detective from Budapest whose unique investigation methods attracted the Imperial Secret Service, also gets involved in the investigation. Constantly following fresh new clues, the strange pair attempts to prevent one of the most tragic events in world history. Meanwhile, they do not even realize that they are to set such tides into motion that will change the life of Europe completely. In their new book, Peter Tarjanyi and Rita Dosek expose one of the 20th-century spy games with the most serious consequences. Is it possible that a mailed letter gone astray changes the destiny of the whole world? How undefended a nation can be if it is betrayed by but a single citizen? How did two Hungarians reshape the course of history?