"A tremendous tale of hushed and unhushed uproars in the linked fields of war and diplomacy" (The New York Times), from the Pulitzer Prize-winning author of The Guns of August In January 1917, the war in Europe was, at best, a tragic standoff. Britain knew that all was lost unless the United States joined the war, but President Wilson was unshakable in his neutrality. At just this moment, a crack team of British decoders...