The discreet stink of the bourgeoisie perfumes the wonderfully mordant, dry-eyed family saga, The Flower of Evil. Claude Chabrol introduces three generations of an upstanding provincial French family, and then watches, poker-faced, as rot from the sins of the elders (including but not limited to murder and Nazi sympathizing) works its way through the family tree. There's a genteel old lady (veteran Suzanne Flon, from Orson Welles' ''The Trial''), who has been keeping secrets for decades; her dauntingly efficient middle-aged niece, Anne (''Venus Beauty Institute'''s Nathalie Baye), who is campaigning to become the local mayor with Hillary Clinton-forged steeliness; Anne's snaky second husband/second cousin, Gérard (Bernard Le Coq); and Anne's unsettled daughter (Mélanie Doutey), who is in love with Gérard's restless son (''The Piano Teacher'''s Benoît Magimel). Nothing good can come from this overwatered lot; nothing does. Yet Chabrol, who untangled twisted emotional roots in ''La Cérémonie,'' nurses the story with such cold delight that even when the plot gets overgrown with accident and coincidence, a compelling odor of moral decay hangs in the air.