The Murderer Lives At Number 21 is a bit like the french version of the Thin Man. Both films are murder mysteries with a wide number of suspects, a comedic tone, and a detective who seems to spend just as much time dealing with his off-beat love interest as he does investigating the case. Pierre Fresnay in turn plays the role of Inspector Wens in much the same way that William Powell played Nick Charles in The Thin Man. Fresnay has a real casual demeanor in his performance as he walks along at an leisurely pace even though there is a murderer on the loose. This in turn is seen through his performance as Fresnay always stays quite calm and relaxed all the time, and treats the whole affair as a game, at least in part anyway.
Fresnay is quite fun in the role actually though and does have that same time of dry delivery that suited William Powell, although Fresnay is a bit less sardonic in style. Fresnay has the same type of charm that is rather unassuming but so perfectly fitting in his creation of the assured detective. Fresnay makes Inspector Wens properly likable with his charm, and his attitude never seems distant rather it simply creates the right relaxed tone for the picture. Fresnay manner also allows him to play well off of Wens's opera singer girlfriend Mila (Suzy Delair) who is rather flamboyant in nature. Fresnay honestly makes Delair's performance work much more, by his manner of downplaying his part, and giving some rather funny reactions to some of her absurdity.
All of it is not fun and games though as technically Wens does need to find a murderer which means going to the boarding house and interviewing each resident to find the culprit. Fresnay keeps the same tone even as the bodies start piling up but he does so in a convincing fashion. In his scenes of examination Fresnay oozes the right intelligence along with the wit in the character. Every line he delivers he brings the right incisive and piercing quality and he illustrates that Wens's relaxed attitude is actually part of his method of keeping the crooks off guard. Fresnay carefully never seems to aloof to the point that he seems that the murders don't matter, there is a substance that Fresnay subtly brings this in some key reactions, and he cleverly brings the dramatic weight well still being so eloquently lighthearted.
Pierre Fresnay makes Inspector Wens a great protagonist for a mystery. It's so easy to follow him through the mystery to its end by creating the necessary tone for the film creating an enjoyable story, but Fresnay goes further than that in making his own performance just enjoyable to watch all on his own. Fresnay is very entertaining throughout but my favorite scene of his is when he uncovers the culprit but not in the best of ways. It leaves Wens to distract the killer by delaying although this seems technically hard to believe its actually completely works because of the way Fresnay controls the scene so completely and so brilliantly. It's a marvelous scene for Fresnay and it shows how good Fresnay is at the role. Unlike the Thin Man, The Murderer Lives At Number 21 was a single effort without any sequels, which is a bit unfortunate as Fresnay made Inspector Wens such delightful company that I would not have mined seeing him on another investigation.