A comic chamber piece as black as midnight and as chilled as its white wine, Beatriz at Dinner works best as a microcosmic look at the self-consciousness of racial identity and less as a pivot into personal tragedy.

It’s the third teaming of writer Mike White and director Miguel Arteta — following their seminally sour indie Chuck and Buck and 2002’s breakout The Good Girl. Their rhythm, such as it was in testing commercially acceptable limits of caustic-comic indie character studies, seems easily resumed here, with a career-best turn from Salma Hayek, another beauty in John Lithgow’s battery of bellicose blowhards and a barbed-wire gauntlet of social commentary.

But as White and Arteta work up a sweat at the whetstone, they sheathe their knives at the worst possible moment, falling back on an oft- (and better-) used music cue to stoke sadness.

Beatriz Luna (Hayek) is a masseuse and alternative healer in California — a Mexican immigrant of whose past we hear secondhand snippets from someone for whom Beatriz was never first priority. She pops personal bubbles with joy (the movie is filled with awesome reactions to unexpected hugs) and extols virtues of ecological preservation as an active connection among all living things.

Spiritually, there’s room in Beatriz’s Volkswagen for Buddha, Jesus and her healing massage table. But when the car breaks down outside the home of longtime clients Grant (David Warshofsky) and Kathy (Connie Britton) — and her faraway friend can’t get there to fix it — she’s pled with to stay for dinner.

After all, Beatriz was a do-gooder rock on whom Grant and Kathy leaned during their daughter’s cancer — all the more charitable a case to parade in front of their friends. Certainly, she will be graceful in her complacence … right?

White’s script excels at its illustration of service-industry professionals as just another type of tchotchke for the uber-rich — glanced at and occasionally dusted, never truly observed or appreciated. Beatriz already feels cosmically and culturally askew, but she’s about have her nose rubbed in it. She soon realizes the meal is celebrating an almost-certain environmental catastrophe in the name of retail development like the one that destroyed her town.

Alex and Shannon (Jay Duplass and Chloe Sevigny), a legislative fixer and his equally sycophantic wife, are there, too.  But the guests of honor are Doug Strutt (John Lithgow) — a self-aggrandizing moneybags with a moral vacuum who has funded the deal and who listens to others only if they support his point.

The extra T in Doug’s name emphasizes that he is to be in no way confused with anything as frivolous as dancing. You’re in My Way, Asshole is a potential memoir title he workshops with Alex and Grant; in this day and age, he’d assuredly get away with it. Doug has opinions and money, so people listen. At his side is his third wife, Jeana (Amy Landecker), who goads Doug into abrasive behavior even as she claims she can’t stand it — her way of manipulating a manipulator.

It’s with Doug whom Beatriz most directly clashes, in ways both tantalizingly confrontational and disappointingly anticlimactic.

Beatriz hangs back from everyone else like a social specter, unseen for minutes on end before she’s confused for household help. Hers is a sincerity, however seething, these people simply cannot stomach. Hayek lets you sense a deep reservoir of anger or a pending psychotic break in Beatriz, along with brief surrealistic visions of smoke-belching factories and oil-stained bays — and the Falconetti-like framing of her in close-up is a smart, sly choice from Arteta.

White’s screenplay, too, suggests the potential, however slim, for communion between Doug and Beatriz — until she, and we, realize his philosophy about animals is merely a cover for another dominion-over-everything argument. She takes Grant and Kathy’s welcoming of him as a personal betrayal, the embrace of an acrimonious man who pollutes as she endeavors to purify.

Just when it’s brought to a believable boil, Beatriz at Dinner fritters away its final moments on a fugue state. At a too-svelte 81 minutes, it’s ultimately an appetizer masquerading as an entrée.