In Reunion Island in the Indian Ocean, the owner of a cigarette factory Louis Mahé (Jean-Paul Belmondo) is engaged through correspondence with Julie Roussel and he does not know her. When Julie arrives in the island to get married with Louis, he waits for her in the docks but Louis does not recognize Julie in the passenger vessel and finds that she is totally different from the picture she had sent to Louis. They get married and Louis shares his bank accounts with her. When Julie's sister writes a letter to Louis asking her sister to write to her, Louis discovers that the woman is not Julie that is missing. Further, he finds that the woman has cleared his bank accounts and left the island. Louis and Julie's sister hire an efficient private detective Comolli (Michel Bouquet) and Louis travels to France seeking the woman, but he has a nervous breakdown in Nice and is submitted to an intense sleeping therapy in a clinic. He recovers and finds that the woman, actually Marion Vergano (Catherine Deneuve), works in the Phoenix Club Privé in Antibes and lives in the low-budget Monorail Hotel. Louis breaks in her room and when she arrives from the club, she tells that she was happy with him but her former dangerous lover Richard had blackmailed her. Louis is still in love with Marion and escapes with her to the countryside. But Comolli is chasing Marion in France accused of murdering Julie.<br /><br />"La Sirène du Mississipi" is a film-noir by the great director/writer François Truffaut, with an unconventional love story of passion, murder and love that hurts. The femme fatale Catherine Deneuve is astonishing, probably in the top of her beauty and is delightful to see her face and the topless scenes on the road and in the room. Jean-Paul Belmondo is very athletic, and the sequence when he escalates the wall of the hotel is impressive. Catherine Deneuve makes this film worth and gives credibility to the passion and lust of Louis. My vote is eight.<br /><br />Title (Brazil): "A Sereia do Mississipi" ("The Mississippi Mermaid")