Pinkerton's National Detective Agency was 19th-century America's premier private police force, the leader of a flourishing industry that offered solutions to the chaos and corruption of the nation's law enforcement. But the Pinkertons were more than just detectives. By the 1890s, they were a private army-on-call for powerful corporations. In the first episode of this two-part series, we'll chart the birth and evolution of the Agency -- from its founding by a radical immigrant in the 1850s to its bloody pursuit of outlaws and Irish labor groups in the decades after the Civil War.