'Bal Cupidon" features a well-meaning female lawyer and an arrogant smug private eye ,half Sherlock Holmes ,half Arsene Lupin,forced to investigate together ,whereas they are at odds with each other (she had him thrown into jail because he showed himself a real menace on the roads).Like it often occurs in today's thrillers,if we are to believe the screenwriters ,duty calls,and ,little by little ,they become reconciled ,and by the end of the story,you guess what happens..