The Spy of the Rebellion follows the activities of Allan Pinkerton, famous American detective and spy, during events leading up to and during the American Civil War. By his own admission, in 1861 Pinkerton led a group of agents who foiled a plot to assassinate President-elect Abraham Lincoln. Later, under the pseudonym of Major E. J. Allen, Pinkerton was in charge of an organization which carried out an intelligence and espionage for General George B. McClellan. The book is filled with the amusing stories about spy work and methods used by Pinkerton to recruit and manage agents.