America in the early twentieth century was rife with threats. Organized crime groups like The Mafia, German spies embedded behind enemy lines ahead of World War I, package bombs sent throughout the country, and the 1920 Wall Street bombing dominated headlines. Yet the story of the one man tasked with combatting these threats has yet to be told. The Life and Times of William J. Flynn is the first book to tell the story of William J. Flynn, the first government official to bring down the powerful Mafia, uncover a sophisticated German spy ring in the United States, and launch a formal war on terrorism. As the Director of the Bureau of Investigation (the forerunner to the FBI), Flynn would become one of the most respected and effective law enforcement officials in American history. Long before Eliot Ness and the Untouchables went after Al Capone and the Italian mob in Chicago, Flynn dismantled the first Mafia family to exist in America.

The success against the Mafia made Flynn famous, with front-page stories about him in newspapers across the country. His rise through the ranks was swift. As Chief of the Secret Service (then an organization devoted to intelligence rather than protecting the president), Flynn, nicknamed "the Bulldog" for his tenacity in pursuing leads, again won national acclaim when he uncovered a sophisticated German sabotage campaign in the United States on the eve of American entry into World War I. As the Director of the Bureau of Investigation, Flynn would devise the first counterterrorist strategy in U.S. history in his investigation of the anarchist terrorists leaving bombs across the country. He would also appoint an ambitious library clerk named J. Edgar Hoover to the Bureau's newly created Radical Division.

Flynn's distinguished career came to an inglorious end, however, when he was unable to find the perpetrators of the infamous Wall Street bombing in September 1920. He never again returned to government service, instead turning to editing a detective fiction magazine called Flynn's that became one of the most popular magazine publications of its time. In this riveting and well-researched biography, the first devoted to the man who became one of this country's greatest detectives, author and terrorism expert Jeffrey D. Simon reveals the fascinating, exciting, and at times tragic story of William J. Flynn.