Shows the facilities and techniques of the FBI and its agent training and dramatizes apprehensions. Reel 1, J. Edgar Hoover introduces the film. Fingerprints and criminal files are shown and explained. Dramatizes events in the capture of John Dillinger. Personages, Homer S. Cummings, John Dillinger. Reel 2 shows prominent persons, places, and objects in the Urschell kidnapping case, dramatizing the apprehension. Shows classroom and field training of FBI agents. Reel 3 shows scientific methods used to gather clues and evidence from murder weapons, clothing, and objects that reveal physical characteristics.