In 1998, William Queen was a veteran law enforcement agent with a lifelong love of motorcycles and a lack of patience with paperwork. When a "confidential informant" made contact with his boss at the Bureau of Alcohol, Tobacco and Firearms, offering to take an agent inside the San Fernando chapter of the Mongols (the scourge of Southern California, and one of the most dangerous gangs in America), Queen jumped at the chance, not realizing that he was kicking-starting the most extensive undercover operation inside an outlaw motorcycle gang in the history of American law enforcement.

Nor did...