I'm not familiar with the Georges Simenon novel which forms the basis of this highly entertaining film but if Henri Decoin was faithful to the original in his adaptation then it is far from the usual Simenon fare and more the territory of Sacha Guitry who actually tackled a similar subject in Quadrille. Set in Cannes the story revolves around the unbearable Annette (Louise Carletti) who falls for handsome lawyer Marcel (Henri Garat) who in turn is pitching the woo to haughty American (and blonde with it) Myriame (Mona Goya) who in turn is attempting to charm the shy Bernard (Georges Rollin). With a brittle script by Decoin even journeyman director Jean Dreville can't knock the gloss of this one and it all moves at a fair clip until the finale which sees Annette getting Marcel to the altar only to ditch him in favour of Bernard. Well worth a look.
Review of Annette et la dame blonde
