He was there when decisions were made that changed history's course before and after World War II. He was Hitler's pianist and would share many of his secrets with the US President Franklin Delano Roosevelt. The figure of Ernst Hanfstaengl, Munich, 1887-1975, remained hidden. It is now that Thomas Snegaroff, a French historian and journalist, illuminates the story by imagining his life in "Putzi." Hitler's confidant (Seix Barral), which traces, incidentally, the Europe of those decades. Hanfstaengl, who was two meters tall, was called a "traiteur" and a "craftsman for evil". His nickname, Putzi in Bavarian, is paradoxical. It means...