Burrough originally intended to make a television miniseries about the Depression-era crime wave in the United States but decided to write a book on the subject instead. Mann developed the project, and some scenes were filmed on location where certain events depicted in the film occurred, though the film is not entirely historically accurate. After killing Charles Floyd, FBI agent Melvin Purvis is promoted by J. Edgar Hoover to lead the hunt for bank robber John Dillinger. Purvis shares Hoover's belief in using scientific methods to battle crime, ranging from cataloging fingerprints to tapping telephone lines.