The perfect family is having the perfect ski vacation. See them pose for photos under the lifts. See stark winter light emphasize Mom and Dad's patrician cheekbones as they nap beside their two adorable children. See them all dutifully use their electric toothbrushes. Wonder if you are watching a J. Crew catalog come to life.

Now see the family lunching on a terrace near the summit. See an avalanche come rocketing down the mountain. Root for the avalanche against the perfect family. Root for this to become a disaster movie.

That's not quite what happens in director Ruben Östlund's Force Majeure, Sweden's official candidate for the Best Foreign-Language Film Oscar. The avalanche turns out to be a controlled one, set off to prevent real disasters. The family on the terrace suffers nothing worse than a whiteout and faces full of snow. But the avalanche, we gradually learn, has brought them disaster — of a smaller-scale, domestic kind, as much comic as tragic.

Östlund's austere style — characterized by long, stationary, painstakingly framed shots — may frustrate viewers in the early going, where we just want something to happen. But that restraint is key to the power of the avalanche scene and its aftermath. At the moment of impact, the screen goes white, hiding the action. When it clears, everything has changed in the relationship between parents Tomas (Johannes Kuhnke) and Ebba (Lisa Loven Kongsli). But it will take them — and us — the rest of the movie to figure out how and why.

At first, the trouble manifests in small ways — a glance askance, Ebba's requests for alone time. She can't seem to tell Tomas what's bothering her. But as they dine with new acquaintances, speaking in a foreign language (English), suddenly the story pours out. When the avalanche bore down on them, Ebba claims, Tomas didn't react as a husband and father should. He showed his true colors. And now that he's proved himself unfit for the patriarch-and-protector role, she doesn't feel like playing her traditional role in this marriage, either.

Tomas stoically denies Ebba's version of events, but cracks start to show in his inexpressive facade. When the couple gets a visit from an old friend and his new girlfriend (Kristofer Hivju and Fanni Metelius), the conflict spirals out of control.

This is no heavy-handed marriage drama. Östlund doesn't tug at our heartstrings by putting the kids in physical peril, and he uses deft editing and musical cues to place an ironic frame around the couple's decidedly first-world problems. When Tomas and Ebba take refuge in the hall so the children won't see them fight, for instance, the same janitor always seems to be watching them, cigarette dangling from his sarcastically curled lip.

Real danger has spared this pair; their tragicomedy is that, like so many of us, they find it hard to live without the easy shorthand of social roles: husband and wife, protector and nurturer. Now they're confronting the echoing hollowness under their masks, and the immense, alien mountainscapes emphasize their pettiness.

Force Majeure ends twice without coming to a real resolution, perhaps because there isn't one. If this were a zombie-apocalypse movie, we would quickly discover which parent is really better equipped to lead the family out of danger. But because it's a low-key, realistic drama — a kind of film Hollywood increasingly doesn't produce — the balance of power remains something for the couple to hammer out, day by day. And the audience comes away realizing that behind every catalog-perfect pairing is something rougher and more real.

(Note: Force Majeure plays at Montpelier's Savoy Theater through December 11. After that, check for it on video on demand, or on DVD/Blu-ray in February.)