(Contains spoilers)<br /><br />People who put a Lonely Heart's ad in the newspaper are often idealists. They try to put into a few words everything they are and expect. The exchange of letters is full of hope...Louis Mahe (Jean Paul Belmondo), owner of a cigarette company on the ile de la Reunion (east of Madagascar) is so affected by the letters of Julie Roussell that he proposes to her. But not the expected pretty brunette comes from board of the "Mississippi", but - Catherine Deneuve. And we know from the start that she is a marriage imposter and that a crime has taken place. She shows no interest in "Julie's" wardrobe (she does not even get her trunk open) and neglects her canary until it dies. But the most basic tricks of seduction (an open zipper) are sufficient to transform Louis into a pliable little dog. First: a joint bank account. And then, when Julie's sister draws attention to herself, the flight. With 27,850 millions of Louis' 28 millions - she would have needed his signature for the entire sum.<br /><br />Louis and Julie's sister engage a private detective (Michel Bouquet). Louis contrives to trace Marion (Deneuve's real name) in Antibes where she works as taxi-girl - her gangster-lover left her penniless, or rather centimeless. Louis finds himself unable to kill her. She tells her story: Orphan. Precocious. Lesbian experiences. Many sugardaddies. Jail - and soon she leads him by the nose again. The detective turns out to be sly as a fox and tenacious as a blood hound; Louis and Marion bury his body in the cellar. They flee to Paris, where Louis discovers that Marion has a costly taste. She worships money like a deity. He sells his firm at a fraction of its value. But when the corpse of the detective is discovered (a flood) they have to flee again - without the money. Life in a mountain lodge, together with a whining loser - Marion can think of a more cheerful life without this appendage...<br /><br />A high point in the careers of everybody involved. Belmondo's self-deceit makes him nearly endearing. Deneuve looks beautiful in her wardrobe by Yves St. Laurent, and her performance is delightful: At first she fakes the fragile wifey - too timid to ask her husband for money, that's why the joint bank account is needed - but after being exposed she sounds like Katharine Hepburn in the jail scene of BRINGING UP BABY. The scenery is spectacular - the tropics, the riviera, Paris. Truffaut directs with self-evident aplomb: the sixties were the only decade when european films were head and shoulders above american productions. After this film Truffaut was able to look his idol, Alfred Hichcock, full in the face.