In the 1920s, Denver was a city coming into its own: a booming economy, a growing population and flocks of tourists. But underneath that vibrancy was organized crime and corruption at the highest levels. The city also saw the emergence of the The Ku Klux Klan accompanied by anti-immigrant sentiment. The new book, "Gangbuster: One Man's Battle against Crime, Corruption, and the Klan" by Alan Prendergast is about that time and about a man named Philip Van Cise who was determined to uphold the law.