Ten years after the publication of his Services Spéciaux (1935–1945), Paillole took up his pen once again in order to shed further light on the critical role that the French Secret Service played in the infiltration of German agencies. In this first English edition of The Spy in Hitler’s Inner Circle, Paillole brings us to the very heart of the world of espionage and counterintelligence, providing unique insight into the key figures that led to the decoding of the Enigma machine at Bletchley and the ultimate collapse of Hitler’s Third Reich, most notably through Hans-Thilo Schmidt, France’s German spy embedded in the very heart of the Third Reich. In compelling narrative style Paillole details how Schmidt delivered intelligence to France right from the source of the German Cipher Office. Schmidt, who’s brother Rudolf occupied one of the highest postings in the Third Reich, commander of 2nd Panzer Army in Russia, created an intelligence network between France, Poland and England, and successfully transmitted crucial details about Hitler’s strategic plans. From information about Germany’s rearmament and the reoccupation of the Rhineland, to fundamental technical intelligence about the Enigma machine, Schmidt’s contributions are key to the Allied victory in the intelligence war, despite the fact that France largely ignored his communications. Revealed here are the most secret aspects of the ‘secret war,’ the ‘war of numbers.’ By way of Hans-Thilo Schmidt Paillole sheds further light on the interaction of secret agents working inside the German government, bringing attention to the cooperation between the French, English and Polish agencies surrounding the challenges of decoding the Enigma machine. We learn the innermost details of the roles that men such as Gustave Bertrand, Rudolphe Lemoine, and Richard Sorge played in this dramatic history and ultimately the pivotal role that Bletchley’s Alan Turing was able to perform as a result. Paillole brings renewed focus onto one of the most important espionage affairs of the war and sheds new light on already existent Anglo-Saxon and Polish historiography, revealing new aspects of the participation of Enigma during the decisive phases of the Second World War: the Battle of France, the Battle of Britain, the Battle of the Atlantic, the Battle of Libya and the Battle of Normandy.