After sending the Molly Maguires to the scaffold in 1877, Pinkerton's National Detective Agency plunged headlong into America's labor conflict. At the vanguard of its war on organized labor was the Protective Patrol, an armed force that deployed to over seventy major strikes. Was the Patrol a lawkeeping elite, as the Agency and its employers claimed? Or, as labor leaders and reformers argued, was it a gang of cold-blooded, mercenary killers? After a disastrous intervention in 1892, testimony in a dramatic Congressional hearing revealed that both sides might have been wrong all along...