Book excerpt: America's oldest law enforcement agency, the United States Secret Service, has never been exposed like this before. The Secret Service has made many headlines through the decades, especially in the last five years. This book presents a thorough look at more than 100 of the most famous, infamous, and interesting agents who have protected presidents from William McKinley to John F. Kennedy to President Trump and everyone in between. Students of history will find much to contemplate in this revealing, entertaining, and sometimes disturbing book. Readers will never look at the men who guard the president the same way ever again.