Though a bit stodgy and stiff, this is an eye-opening and authentic-feeling window into the work of FBI counter-espionage in NY as they attempt to keep nuclear secrets from Hitler. The stentorian voice-over re-occurs throughout the movie and there are thrilling shots of 1940s NY streets throughout that are lensed in a more modern style at times. The acting is merely serviceable, esp. The cookie-cutter hero but some of the German characters come across as being truly menacing and sinister (while not over-doing it); special mention must be made of Signe Hasso who's perfect as the ice-cold mistress-spy. What I guess lends this film its noirish edge is its complex network of characters and schemes, and the sense of paranoic dread which raises its ugly head in claustrophobic scenes. It's amazing to see all the pre-digital paperwork, organisation and deception that had to be done to track these dastardly spies down - but it's not just procedural bureaucracy-there is a real sense of tension threading its way throughout the movie and the action becomes quite edge-of-the-seat stuff here and there (even if only on a small scale between the spies). The 90 mins or so go briskly by as you watch this highly unusual type of movie.