For a police thriller, this movie chose the strange angles of architecture and fashion from which to tell the story. Throughout, the film actively tries to showcase a new, modern France. In the weird opening sequence, we see a sea-side resort with an endless row of brand-new apartment blocks, totally void of human presence in a foul winter-weather. Strangely, from afar, a shop in one of the buildings seem open. Because of the abundant lighting, we might be tempted to think it's a bar, but it's a bank (about to be robbed). The police headquarters is another modern building given lots of camera-attention by Melville, who seems to juxtapose this 'new' France to the old; the contrasts with scenes of the 'old Paris' such as the closing scenes at the Arc de Triomphe are great.
The male characters seem to spend an inordinate amount of time to groom their looks. Both Alain Delon and the excellent bad guy Richard Crenna (Simon) are given lengthy shots showing them combing their hair. They parade around in flawless suits, slick ties, lush bathrobes, gold cuff links. These are sharp dressed men, vain and self-obsessed, misogynist and gay-bashing. The gorgeous can-can girls are there (like in so many other Melville movies) but no-one seems to notice them. Delon manipulates a beautiful transvestite into thinking he might fall for her charms, only to beat her up when she fails to deliver on a promise.
Catherine Deneuve on the other hand seems less well served, sartorially speaking; I was not very impressed with her acting performance in this film, but perhaps my judgment is influenced by the ugly earrings she wears throughout. The closing titles highlight that the black dress worn by 'Mademoiselle Deneuve' was by Yves Saint Laurent. I don't know why this was pointed out, since the dress is hideous. Deneuve's finest moment was when she plays an angel of death, wearing a haute couture caricature of the nurse uniform. Quentin Tarantino must have been directly inspired by this to create Daryl Hannah's nurse look when she is set to murder Uma Thurman at the start of Kill Bill vol 1.
All in all, the plot was not that interesting, but since the male actors were all in terrific form it was a very pleasurable movie to watch.