What is the author's tone in the biography, The Notorious Benedict Arnold?

This is a non-fiction book, which means the storyline consists of facts ranging from Benedict Arnold's background and childhood to his death. Author Steve Sheinkin opened the book with a scene in which British General John Andre was marched to the gallows for his execution. This scene set a somber tone for the book, ensuring the reader remembered that the overall story was serious with grim consequences.