During WWII, Hollywood made hundreds of films aimed at solidifying the public's support for the war. Some of these were extremely well made while others often made the Japanese or Germans seem semi-human and rather stupid. These less well made and less realistic films often were, in spire of themselves, quite entertaining...but also very obvious in their aims. When I saw "Secret Mission" I realized that the British, too, could make ridiculously unrealistic propaganda films....and while the Nazis aren't quite as cartoonish as some of Hollywood's Nazis, they were incredibly stupid...so stupid you wonder how they ever took over most of Europe!!
The story involves some British spies as well as one French one (James Mason of all people) who sneak into France in order to survey the area before an upcoming invasion. The Nazis are uniformly dim...having very lax security and falling for pretty much every lame attempt at subterfuge! The Germans are SO dumb that it really takes away from the movie...and doesn't show how efficiently evil they really were!
So is it any good? Well, it's not terrible...not that this is a glowing endorsement! Overall, despite some very fine actors (such as MIchael Redgrave, Herbert Lom and Roland Carver), a relatively dull offering...one that is watchable but not much more.