Horror films divide moviegoers into love ’em or loathe ’em camps, and I confess to being in the former. If you’re an aficionado who appreciates horror’s unique mix of camp and catharsis, The Descent is for you. Director Neil Marshall masterminded a 2002 scarefest, Dog Soldiers, in which a platoon of British Special Forces trainees on a practice mission in the Scottish Highlands were beset by a pack of werewolves. His new movie puts forth a similar scenario; but this time the group in trouble consists of women, and the dread is deeper, murkier, and altogether more dreadful.

The film follows six outdoorswomen-buffed-up rock-climbing and rafting types-on a spelunking adventure deep in the Appalachian woods. Things quickly go awry. The women lose their way in the immense caverns, and after a long crawl through a narrow passage, a cave-in seals off the way out. Panic mounts when the hubristic leader, Juno, confesses she has led the group astray; this isn’t actually the cave they set out to explore (and where park rangers might mount a search), but another cave altogether, uncharted and unknown. No one knows where they are, and there is no way back. The only hope is to plunge deeper in.

The sense of stricken entrapment is suffocating, and this could have been simply a survival thriller, along the lines of 2004’s Touching the Void. But Marshall goes a step farther. Not only are the women trapped, but...they’re not alone. Halfway through the movie, we begin to catch fleeting glimpses of someone watching them. The watchers seem not entirely human. How scared can you be? Adroitly The Descent piles on overlapping dreads: claustrophobia, fear of the dark, even fear of heights (precipices over deep inner canyons). And now this?

There’s plenty to admire in this lean, low-budget film. Marshall keeps his characters sufficiently fleshed out to establish conflicts that heighten the tension once things go wrong, bringing old grudges to the surface and triggering bursts of recrimination. Seasoned thriller and horror fans, meanwhile, will appreciate nods at classics of the genre-an early overhead tracking shot of a car driving through the woods echoes the opening sequences of The Shining, and a sanguinary deluge pays lurid homage to Carrie. The travails of urban outdoor enthusiasts lost in a hostile Appalachian setting conjures Deliverance, John Boorman’s 1972 survivalist epic. The Descent provides a witty riff on Darwinian ideas. The mutants in the cave have adapted, and now the women must also-much more quickly. Who, if anyone, will emerge fit enough to survive?

It’s interesting to note that the movie was made without computer enhancement. Since digital wizardry began transforming what we see on the screen, it has become harder to be impressed, and to be scared. Knowing that the mutants in The Descent-slimy, translucent crawling forms with horrible blind eyes-are the work of makeup guru Paul Hyett, and not some keyboard prestidigitator, somehow makes them more believable. The Descent is heart-poundingly scary, and as it rushes to a close you experience the blessed relief of waking from a bad dream. If any of the women survives the ordeal in the cave, she will be haunted by it forever, while we are glad to reach the well-lighted lobby and begin to shake it off.

Being trapped in a cave with strange creatures might also describe Little Miss Sunshine, Jonathan Dayton and Valerie Faris’s antic satire of the American family. The comedy stars Greg Kinnear as Richard Hoover, a would-be motivational speaker, Toni Collette as his beleaguered wife, Alan Arkin as his randy, irreverent father, and Steve Carell (of TV’s The Office) as his clinically depressed brother-in-law, a renowned Proust scholar who has recently attempted suicide following professional and romantic disasters. Completing the motley crew are a morose and resentful teenaged son, Dwayne (Paul Dano), and seven-year-old Olive (Abigail Breslin), a chubby, frumpy, bespectacled little dumpling who dreams improbably of competing in a children’s beauty pageant. When a last-minute cancellation opens up a slot in the contest, Olive gets the nod, and the entourage sets out in a broken-down VW bus from their home in Albuquerque, headed for L.A. Little Miss Sunshine takes one spectacularly dysfunctional family and sends it forth on a rollicking road trip. Think The Royal Tenenbaums meets Chevy Chase, and you pretty much have it.

The Hoovers are not exactly high achievers. Dad retails his how-to-win philosophy, with its nine points, to near-empty rooms in local schools, while Dwayne, his hair dyed jet black, remains sunk in a perpetual goth glower, reading Nietzsche and refusing to speak-at all. Grandpa has recently been kicked out of Sunset Manor for snorting heroin. Like The Royal Tenenbaums, Little Miss Sunshine dishes out a lot of quirkiness, but what it does with it is both funnier and more biting. You laugh, but you wince as well; you can’t help feeling at least partly implicated. One early scene captures the casual degradation of the American dinner table. Like so many families, the Hoovers lack time, money, and manners. Dinner is a bucket of take-out fried chicken tossed onto paper plates, conversation is a crisscrossing blast of complaint. WELCOME TO HELL! Dwayne writes on his pad and flashes it to Frank.

Richard, meanwhile, furiously repackages the misery of his family into tidy messages of uplift. “I think we could learn something from Dwayne,” he opines at his son’s snarling, morbid fantasy of becoming a fighter pilot. “Dwayne has a focus. He has a dream.” Faris and Dayton place Richard’s absurd and relentless cheerleading at the center of their satire, portraying it as both a pathetic attempt to make reality conform to the shape of his nine points, and as the flip side of a harsh personal judgment. “Uncle Frank gave up on himself,” he announces when Olive asks Frank why he tried to kill himself. “That’s something winners never do.” The film has at its core a savvy deconstruction of the American ideology of winning. It’s painful to watch Richard’s hysterical mantra (“There’s two kinds of people in this world-winners, and losers!”) extend even to Olive, as he hectors her for eating ice cream (fat people are losers) or for mumbling to a waitress (“Don’t apologize, it’s a sign of weakness”). In Richard, the idea of winning has become pure pathology.

The backup characters in Little Miss Sunshine function perfectly, posing darkly comic relief to Richard’s overbearing optimism. Arkin is brilliant as Grandpa, a grizzled libertine who reads porn mags and gives lewd advice to Dwayne. Dano’s Dwayne hints at inner rage and fantasies of violent revenge-when he hears his parents arguing in the next room, a blissful smile spreads over his face. And Carell’s Frank, semi-catatonic with depression, surveys all with a baleful, thousand-yard stare. The film adopts a teen’s jaded view of adult affairs, and essentially sets itself up as a coming-of-age story-for the whole family. What will happen to break down the antitheses of winner and loser, optimism and nihilism, and synthesize for the family a more capacious sense of itself? The key, of course, is Olive, whose innocence opens up a way out.

Given how schematic this all sounds, the result is surprisingly effective. The film’s ending combines madcap hijinks with a take on authenticity that may strike some as a tad therapeutic. It’s sentimental and silly, but it’s endearing as well, and it gets to you. Little Miss Sunshine plays the crowd for plenty of laughs, but it has an idea in hand. America, Brazilian filmmaker Hector Babenco once remarked, lives under a dictatorship of happiness. The Hoovers are a cautionary lesson about being trapped in the ideology of success. Not until they learn to fail will they free themselves; and in this hilarious and painful film Dayton and Faris give them the occasion to do so, and to do so gloriously.