The war years saw a lot of "pretty good" movies, relatively innocuous stories, usually good entertainment, the sort one would rat 4-7, with a few poorly directed slow moving ones a little less.
And it's unfortunate that movie makers post 1965 sought to emulate the slow pace dull ones. It would take 30 years for film makers to learn their mistakes. Such was their incompetence. A man on the street could have done better than 98% of producers, directors, and writers from 1965-1995; it was truly the error of "rich kids and children with the silver spoon" at the reins.
But these war years were full of fairly safe vehicles. Some were smartly done, like this murder mystery.
We have a mystery here that begins with the comedy and affable personalities first, then goes into the plot, and that's what makes the atmosphere style murder mystery work.
This is expertly done, and could be used for a film class to show how to make a film. It is "Entertainment".