Starring Asia Argento and Fu’ad Ait Aattou. In French with English subtitles. Rated 18A. Opens Friday, July 25, at the Park Theatre

Hot-blooded young noblemen squandering their substance on steamy courtesans was a convention of 19th-century French fiction. When played in the comic vein, these stories would invariably end with the hero marrying a well-dowried, baby-faced virgin while his erstwhile lover accepted the protection of a much older, but richer, patron. When played as tragedy, the mistress would nobly surrender her sexual claim, then slink off to the nearest garret to die of syphilis or tuberculosis.

Because this is a Catherine Breillat film, neither of those expectations is actually fulfilled, although they haunt the proceedings like spectres at an orgy.

Taking Jules-Amédée Barbey d’Aurevilly’s 1851 novel as its starting point, The Last Mistress pivots on the passion binding Ryno de Marigny (Fu’ad Ait Aattou) to the notoriously hot Vellini (Asia Argento).

Everyone agrees that before Ryno can marry the beautiful Hermangarde (Roxane Mesquida), he must first sunder his 10-year liaison with the aforementioned Spanish seductress. Somewhat reluctantly, Ryno agrees, but what is promised by the mouth is not necessarily confirmed by the blood. Thus, what was once merely a minor peccadillo becomes an irresistible, socially condemned emotional conflagration.

As always in Breillat’s universe, sexual desire is both magnetic and disastrous (in many ways, she’s like a more downbeat Franí§ois Truffaut). Nevertheless, the writer-director does manage to convincingly marry her own vision to that of d’Aurevilly (not as difficult a feat as it might seem, since both artists are self-proclaimed “dandies”).

In other words, the director’s first period piece must be considered an unqualified success.