The Phantom Of 42nd Street from PRC is a not too bad murder mystery of a group of people connected to a theatrical company. Theater critic Dave O'Brien is on the job reviewing a play when the first murder is committed. He gets drafted into the job of covering this and the other murders as they are committed. The ultimate target seems to be Alan Mowbray who is the actor/manager of the company and his daughter Kay Aldridge.
It all goes back to some dirt done the murderer many years ago by many members of the company both in front of and backstage. The culprit has gone quite nuts about it, no doubt fixating for many years on how he would do the job. It is a he, I'll give that much away.
Having a critic be a detective is an intriguing plot premise. Surprisingly the cops seem to warm up quickly to the outside help they're getting unlike in so many of these mysteries.
At a major studio this might have been a minor classic with a lot of the holes in the plot not existing. Still for a PRC film it's far from the worst I've seen.