Fascinating, but Unfocused 
 "Could almost be a novel!" This is a frequent comment for Erik Larson's non-fiction books exploring the intersection between historical moments and private lives. And it is true of this one, in a way. Wisely keeping the 90 pages of sources and footnotes to the end, Larson writes in short, vivid chapters that are compulsively easy to read. But it is also false; no first-rate novelist would have written a book that so divides its focus between its various subjects, or fails in large degree to illuminate the inner lives of its characters. 
 The historical moment here is certainly a significant one: Hitler's first year as Chancellor in 1933-34, a larger subject than either the 1893 Chicago World's Fair ( 
 The Devil in the White City 
 ) or the 1900 Galveston hurricane ( 
 Isaac's Storm 
 ). It is a subject that has been written about many times before, of course, by historians whom Larson freely acknowledges. What makes his book special is its viewpoint--that of a figure who is simultaneously a detached observer of German politics while being compelled to interact with them: the American Ambassador, William E. Dodd, who arrived with his family in July 1933, four months after Hitler had taken power. Larson conveys well the renewal of energy the Dodds encountered in Berlin at the time, and its gradual erosion by fear. His vignettes of the Nazi leaders and other leading Germans are fascinating when there is some first-hand connection (as in face-to-face meetings with Hitler or Goring), less so when he is merely repeating known history. And because he is writing with the eye of an historian rather than a novelist, he cannot penetrate very deeply into the minds of the ordinary people who were swayed by Hitler and enabled him. 
 Larson's books rise or fall on the personal aspect: the private individual in the public setting. Here, I would say, he has two competing protagonists, both interesting in their different ways, but who weaken rather than strengthen each other when placed side by side in the same book. Dodd traveled to Berlin with his wife and son, who virtually disappear from these pages, and also his 24-year-old daughter Martha, who was as flamboyant as her father was restrained. The private/public theme plays out well in the character of Ambassador Dodd. He was a history professor at the University of Chicago before Roosevelt tapped him for Berlin (the last of many choices). He found himself torn. On the one hand was his own concept of the post, possibly shared by the President: to offer a personal example of American decency and modesty. On the other was the view of the Harvard/Yale elite in the State Department: to maintain a dialogue with the regime at all times, even at the expense of personal scruples. It is a fascinating subject that cuts to the core of American values, but it requires a soberly nuanced focus to make the most of it, for unfortunately Dodd himself is something of a gray figure; you have to look hard to find him. 
 Martha, by contrast, is anything but gray. Indeed, she is so brightly colored that you would think her incredible in a novel, did you not have the support of her own (possibly exaggerated) memoirs. Her promiscuity would raise eyebrows even today, but for a woman of that time and in such a position it is extraordinary. At one period, virtually overlapping in her bed, she was having affairs with a French embassy official, a Russian spy, and the head of the Gestapo. She was even set up as a possible date for Hitler, though the episode goes nowhere. A novelist would have given Martha and her father two separate books, probably with different publishers and different marketing. An historian could have done this too, but Larson chose not to. So I would close a chapter on a quiet walk with the Ambassador near his house on the Tiergarten (the Berlin park that is the "Garden of Beasts" of the title), and turn immediately to Martha, resentful that her flagrant lifestyle had little to do with the serious issues of the time. But then, after a few pages with her, I would turn back to Dodd, and have to search for him, hidden in the middle-American decorum of his world view. True, you could say that the contrast between decency and excess in the Dodd family paralleled the contrasts in the Germany of the time, but it would have been much stronger if Dodd had addressed the issue in his own household. However, he seems either to have been unaware of his daughter's behavior or reluctant to confront it. 
 The result is a book with at least three separate elements (Dodd, Martha, and the Nazis), each with ample potential interest, but treated in such as way as to reduce each other's impact rather than cohere into a whole.