The "Commies In NYC" Story at the End is the Beginning of "Bridge of Spies"
For matters of comparison, check out how the true story of Communist spies passing secrets hidden in coins plays in the final part of "The FBI Story" versus how Steven Spielberg and his writers treated the tale 56 years later in "Bridge of Spies."
In The FBI Story, made at the peak of the Cold War, the Commies are dangerous enemies "right within our midst, living among us" and James Stewart's lugubrious narration makes them seem slimy indeed.
The Commie is played by a thug-like guy in The FBI Story(one of the two killers in Bullitt); but in the Spielberg film, he's a quiet, gentle, amusing man played by Mark Rylance in the role that won him an Oscar.
Bridge of Spies takes note of Cold War tensions and of lawyer Tom Hanks desire to keep the Commie on ice to trade for captured spy U-2 pilot Gary Powers, but everything about the story plays much "nicer" in the Spielberg film than in the Stewart film. What a difference half a century and the fall of the Soviet Union makes!