Rare is the vintage French history-of-champagne romance that winds up in the loving hands of tiny distributor Vertical Releasing. So when a “Widow Clicquot” comes along, one simply must pop a cork and indulge. One must.

Director Thomas Napper earned his period-piece bones as second unit director on Keira Knightley’s “Pride & Prejudice” and “Atonement,” and he gives American Haley Bennett (“Swallow,” “The Girl on the Train”) the full Keira treatment in this melodramatic story of undying love, fine wine, property and madness during the Napoleonic Wars.

Barbe-Nicole Ponsardin fell madly in love in her arranged marriage with the mercurial vintner and heir François Clicquot (Tom Sturridge, magnetic and disturbed) in this story’s telling, a woman swept up in her manic husband’s experiments to select and nurture the right vines, and bottle the perfect the wines from his Champagne region winery.

For reasons not made completely clear, he wants to call her “Emily.” But then, he sings to the grapes on the vine, strolls about barefoot and his mop of unruly hair always seems ’80s-album-cover soaking wet.

Perhaps he died of pneumonia or “consumption.” Ah, there lies a tale.

So the story of their love and is told in flashbacks in this film, which follows his widow through her trials — figurative and literal — trying to keep the vineyards and winery because “François lives through his vines.”

It’s the early 1800s, and women simply did not run businesses in Napoleon’s Imperial France. But Barbe-Nicole was there, tasting and testing wines with her husband, offering opinions and absorbing some of his “radical” liberated ideas of how to produce great wine and to manage a successful business, and bringing her own to the table, once she has the chance.

She does this over the objections of her huffing father-in-law (Ben Miles at his prickliest), who has designs on selling the vineyards to the Champagne-dominating tycoon Moët (Nicholas Farrell of “Chariots of Fire”).

Besides, a broker snipes, with other snippy men present, “It’s not your place” to do this work.

But she will not surrender her rights to what her husband promised her was “the most beautiful vineyard in all of Champagne.” With a little help from her former nurse, now maid (Natasha O’Keeffe, luminescent) and her husband’s confidante, his wine broker pal Louis (Sam Riley, giving the man dash, sensuality and edge), she will get around Napoleonic sexism, Napoleonic trade embargoes and Napoleon’s destiny to blend, bottle and market the finest wines in all of Champagne, famous all over the world.

Bennett makes a plucky, perhaps guilt-stricken, perhaps martryed heroine here. Lots of black mourning wear and Empire waistlines park this most Florida Gal of film stars firmly in the era of Austen and Bonaparte. Director Napper and French cinematographer Caroline Champetier (“Of Gods and Men,” “Holy Motors”) frame her in shots best appreciated as resembling painted cameos of Jane Austen heroines.

And Bennett impresses, first scene to last. There’s steel beneath her poker-face as the Widow Clicquot faces down the patriarchal hierachy of “management” styles of the nobles/peasants (even post-Revolution) age, taking ownership of that which will distinguish her as a businessWOMAN, a simple “ability to listen” to the best ideas in the vineyards, in the grottos and in the bottling and selling.

In the flashbacks, her future widow is moon-eyed with love. “I should like to lie at your feet and die in your arms.”

Napper ensures that Eric Dignam’s script, based on the book about the widow, mixes love and lust with personal and professional intrigues. The picture takes on a dreamy quality as we see this woman’s mettle tested time and again — by a war, bad luck and bad intentions on the part of the patriarchy.

Rare is the drama that romanticizes as it teaches winemaking, that serves up mystery and suspense in its plot, all in a film that doesn’t miss a period-piece note. Not one.

It won’t be in theaters long, but add this sparkling bio-pic to your to-watch list, preferably paired with a non-Moët bottle of the wine famous for its tiny (not “frog-eyed”) bubbles.

Rating: R, sex, nudity

Cast: Haley Bennett, Tom Sturridge, Ben Miles, Natasha O’Keeffe and Sam Riley

Credits: Directed by Thomas Napper, scripted by Eric Dignam, based on the book by Tilar J. Mazzeo. A Vertical release.

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