What is the author's style in In the Garden of Beasts: Love, Terror, and an American Family in Hitler's Berlin by Erik Larson?

In the Garden of Beasts is the story of William E. Dodd, who served the country as US Ambassador to Germany from 1933 to 1937, during the time Hitler was rising to power and Nazi aggression was threatening world peace. The book is a historic account of the Ambassador's tenure and is supported by hundreds of sources and references. The author of the book, Erik Larson, who is a national best-selling author and a master of narrative non-fiction, has written an interesting and honest account of the dawning of a historic era.