Seraphine de Senlis is a fairly obscure figure, but she can be numbered among the early twentieth-century painters that Wilhelm Uhde, the art critic who discovered her, called “modern primitives.” But though this sensitive, beautifully crafted if somewhat lugubrious film doesn’t neglect her work—mostly idiosyncratically rendered groupings of flowers bursting with unusual color—it’s more interested in crafting a portrait of the woman herself, a simple, hard-working, frumpy manual laborer who fell into madness after achieving the beginnings of recognition for her painting—and a little wealth.

Writer-director Martin Provost is supremely fortunate in his star, Yolande Moreau, who gives a remarkable performance as Seraphine, introduced in middle age as the film begins in the years immediately preceding World War I. Stout, unkempt and reticent, she works uncomplainingly as washer-woman, maid and cook to local swells in the small town of Senlis, surreptitiously painting with colors she mostly concocts herself from blood, wax and other natural ingredients because—so she says—her guardian angel instructed her to. (She’s extremely pious, though in a fashion that has vaguely pantheistic overtones.) She’s assigned by one of her employers (Genevieve Mnich), a woman who’s already dismissed a painting of hers as inconsequential, to cook and clean for a new renter in the area, Uhde (Ulrich Tukur), who in time recognizes the woman as an untutored talent and befriends her. But World War I intervenes, and Uhde is forced to leave Senlis with his sister Anne-Marie (Anne Bennent). Seraphine remains there, continuing to paint—and work—through the conflict and beyond.

The plot picks up a decade-and-a-half later, as Uhde returns to Senlis and finds Seraphine still painting. He becomes her patron, and she begins living rather higher on the hog than his modest support payments can bear, particularly after his own fortune suffers after the crash of the late twenties. The change of fortune sends the poor woman into an emotional tailspin, and she winds up in an asylum, gaining a modicum of fame only posthumously.

“Seraphine” obviously won’t take a place among a “great artists” festival; its subject was far too minor a figure for that. But Provost and his co-writer Marc Abdelnour aren’t interested in doing an art history lesson. They want to tell the story of a sort of idiot savant of the early twentieth century, a person of little if any intellectual depth but possessed of a natural gift that might not have been appreciated in her own time except by a discerning few, but can be seen with sharper eyes by posterity. In the process they go off on digressions that may be interesting in themselves, but tend to take the film off track, especially as they tend to be treated so allusively: much of the material dealing with Uhde, including his relationships with his Anne-Marie and with his lover Helmut Kolle (Nico Rogner) frankly seems extraneous.

And yet the kernel of the picture—the story of Seraphine herself—remains fascinating, largely as a result of Moreau’s incredibly committed and convincing performance. She inhabits the character so fully and so fearlessly that the portrait she draws, in few words but masterfully chosen gestures—even her walk is revealing—is indelible. With her “Seraphine” is memorable; it’s difficult to imagine it existing without her.

And while the rest of the cast, most notably Tukur, seem content to stand aside and bask in her glow, visually she’s supported admirably by Laurent Brunet’s gorgeous cinematography, which uses the locations to best advantage, and Ludo Troch’s admirable editing. Costume designer Madeline Fontaine deserves a special nod, too.

“Seraphine” may be about a minor artist, but it’s a major success.