George Brent and Basil Rathbone working together to debunk a Nazi sabotage enterprise to stop American help from going to England in the beginning of the war (before Pearl Harbour), being both intrigued by that lovely Hungarian singer Ilona Massey, who in the film is a Norwegian called Carla Nillson, but all her lovely songs are in Hungarian. It's actually the music which is the best in this film, beautifully composed and mainly arranged on classical pieces by Chopin and Liszt, but Ilona Massey's voice is really a wonder of beauty, like all her acting and appearance. This was before Basil Rathbone was established as the ultimate Sherlock Holmes, but George Brent is always completely reliable, whether as a hero or as a villain, but usually he was quite normal, as he is here. Of course, you could question the espionage technique going on here, appearing to be extremely advanced, but turning music into a system of code is rather far-fetched, although most intriguing and attractive, especially as the music is glorious indeed all the way through. Great entertainment with even some excitement and a few murders on the way, but of course, Ilona Massey as an international lady of exceeding culture, beauty and integrity objects from the start to any murders done for the cause.