"Halfway to Shanghai" is a B-movie from Universal Pictures. And, like a B, it's about an hour in length, features mostly unknown actors and was quickly made. Since it was made during WWII, it's also not surprising that there is an element of propaganda within it as well.
The story is set aboard a train in Asia (I assume China or Burma). On board are lots of folks with a variety of backstories that you see and hear about as the film progresses. However, a few are also Axis spies or pro-Nazi and not surprisingly, there is some intrigue and even a murder. Can our Burmese version of Charlie Chan solve the mysteries and help the Allies?
The film benefits from having George Zucco. While nearly everything he did was a B-movie, he was an excellent actor...particularly playing villains like he does here. The rest of the actors and acting are pretty much uninspired...but there's enough Zucco to make Zuccophiles happy. Easy to watch and mildly enjoyable.