This is a murder mystery, with Mr. Moto, for those of you who don't know, as the crafty man investigating the case. Like Charlie Chan, he's a private investigator.
Peter Lorre had a "cool" charisma about him, much like Basil Rathbone, Humphrey Bogart, and others who played such roles.
Films like this either take one or a combination of two of the following: 1. Mystery with clues that the audience can use. 2. Mystery with atmosphere and humor 3. Mystery with a twist.
Just about none have all three. One may cite "Chinatown" as a possibility, but the atmosphere isn't what I would call strong in that one. Atmosphere and humor come either without twists or without clues.
This film uses the first two elements. It would be far fetched to say there is a twist. There is an abundance of atmosphere and humor, and many clues.
We know very soon who the killer is. At first it isn't easy, because all of the suspects look alike, middle aged white men with mustaches, but once we tell them apart, and once the atmosphere is established, we do know which one it is.
That doesn't take away from the adventure, though. Lots of good elements make this an enjoyable film.