George Brent ("Hanley") and Basil Rathbone ("Oliver") work quite well together in this fast moving, if very wordy, espionage thriller. Both are charged with working together to thwart a Nazi plot to interfere with the flow of vital aircraft from the USA to Britain during WWII. It takes all of their wit and guile to discover and penetrate this highly secretive and effective ring of saboteurs, but unfortunately we don't need to do much guessing ourselves which is a shame. There is a strong supporting cast from Ilona Massey ("Carla"), Gene Lockhart ("Grenner") and the usually reliable George Zucco ("Webster") and the theory behind the plot is quite interesting (and musical). It is too long, but it is a bit different, this, and made at the start of the war, it has shades of propaganda to it. Tim Whelan uses the cast well, providing a decent outing for all concerned that has just enough jeopardy to compensate for the fact that it was clearly produced to a tight budget and production schedule. If you like the genre, then you could do a lot worse than sit through this rarely seen example of Anglo-American wartime co-operation.