A rich bourgeois has died:is it suicide or murder?As he cheated on his wife ,and was about to divorce from her,the lady (Michèle Morgan) is the main suspect.
Claude Lelouch,who is ,at least to my eyes, a minor French director ,is at his best when he tries his hand at light thrillers or comedies ."Le Chat et la Souris" recalls "le Voyou" ,with its construction which looks like a puzzle ,its screenplay "à Tiroirs" and even the movie in the movie trick .Lelouch really plays cat and mouse with the audience as Detective Lechat (sic)(Regggiani) does with his still attractive suspect (or is it the other way about?).
There are plenty of funny scenes and some witty lines ("you see this distinguished lady riding a motorbike?");and the nail in the Rum Baba in the chic restaurant is a good idea to provide the detective with the final clue (so to speak,for "nail" is "clou" in French).
Objections: there are not enough scenes where Reggiani and Morgan are together ,and the scenes of the detective's private life (and his assistant's ,played by Philippe Leotard)get in the way.
This film accounts for the difference between Lelouch's world and ,say ,Chabrol's. The latter ,in his best works ,ferociously attacks the bourgeoisie.Lelouch,on the other hand ,makes sure the bourgeois moral is intact.Thou shalt not covet other people's possession.