Charles Booth received an Academy Award for his work on this initial drama-documentary that portrays the FBI’s pursuit of a pre-existing group of Nazi sympathizers already functioning within the United States. The story centers on agent "Bill Dietrich" (William Eythe), who must go undercover and uncover the person responsible—the enigmatic "Mr. Christopher." Under the supervision of "Insp. Briggs" (Lloyd Nolan), he n…