The long reign of Kansas City political boss Thomas J. Pendergast came to an end in 1939, after an investigation led by Special Agent Rudolph Hartmann of the U.S. Department of the Treasury resulted in Pendergast's conviction for income tax evasion. In 1942, Hartmann's account was submitted to Secretary of the Treasury Henry Morgenthau, Jr., in whose papers it remained for the past fifty-six years unbeknownst to historians. While researching the relations between Pendergast and Franklin D.

Roosevelt, Robert H. Ferrell came across Hartmann's landmark report - the only firsthand account of the investigation that brought down the greatest political machine of its time, possibly one of the greatest in all of American history. Reading like a "whodunit," The Kansas City Investigation traces Pendergast's political career from its beginnings to its end.