Around the world, his name is synonymous with security and protection. The legendary agency he began nearly one hundred and fifty years ago is still in operation today, as are many of the surveillance and infiltration techniques he originated. His company's trademark symbol, a large, unblinking eye, inspired the term private eye. Born in Scotland, Allan Pinkerton arrived in America with a solitary silver dollar in his pocket and - as legend has it - the law hot on his heels. A cooper by trade, he might have spent his life making barrels but for a fateful trip in the summer of 1846. On an uninhabited island, where he had gone to cut saplings for barrel staves, Pinkerton happened upon a thicket where a blackened patch suggested a recent fire. To Pinkerton, it also suggested something was amiss. In what became his very first case, the young cooper employed his acute powers of deductive reasoning, patience, and perseverance that would become the hallmarks of his modus operandi. His dogged determination (and several damp, cold, lonely nocturnal vigils) paid off when a gang of counterfeiters was discovered. The modern detective was born. Through four decades of tumultuous history, Allan Pinkerton left an indelible mark. From the Underground Railroad to the Chicago underworld to Pennsylvania and the civil unrest of the notorious Molly Maguires, he took on bandits, bank robbers, kidnappers, spies, and even Jesse James himself. His role in the Civil War was critical: as Lincoln's spymaster, he managed a network of spies who worked behind Confederate lines and tackled espionage at the highest levels in Washington itself. In particular, James Mackay's scrupulously balanced account challenges the conventional view of the controversy surrounding Pinkerton's role in the Peninsular campaign of 1862. Was poor intelligence responsible for prolonging the war?