Combining the requisite demolition-derby thrills with surprising emotional pull, Deep Impact is the best of the recent disaster-movie crop, which includes Twister, Firestorm, and last year's lavapaloozas Dante's Peak and Volcano. That's not exactly high praise. Deep Impact never transcends the genre: You'll still find the same stock structure and a few of the unintentionally funny moments you'd get in a vintage shake-'n'-baker like Earthquake. But it does offer above-par acting, an irresistible what-if premise, and a refreshingly grave tone that treats the onset of human extinction as something more than a CGI holiday.

In spirit, Deep Impact is a throwback to ambitious '50s sci-fi fare like When Worlds Collide, from which it basically borrows its plot. A comet the size of Mt. Everest is discovered by amateur astronomers, whose jubilation is tempered somewhat when they discover the damn thing is due to smash into the earth. When an outer-space demolition effort modestly named the Messiah succeeds only in splitting the comet in two, the stoic U.S. president (Morgan Freeman, our dream commander-in-chief) announces a national lottery that will shelter a million lucky so-and-sos in a network of underground caverns. (In Europe, Asia, and Africa, it's every man for himself--like anybody cares about the rest of the world.) Everyone left on the surface will drown, freeze, burn, or starve.

If Deep Impact had actually shown us those caverns, or let us in on the lottery process--I'd love to have seen the haggling over the 200,000 preselected "artists, teachers, and scientists"--it might've been a true classic. Instead, the script, written by the high-minded duo of Bruce Joel Rubin and Michael Tolkin, is pretty much what you'd expect if you crossed the weepy sentimentality of Ghost with the quasi-religious solemnity of The Rapture. (The spaceship ain't called Messiah for nothing.) By setting the story on a blatantly biblical scale, Rubin and Tolkin have bitten off more than one two-hour blockbuster can deliver.

And yet the movie's earnest, intense seriousness works in its favor. Complaining about the routine characters in a disaster movie is like picking apart the dialogue in a porn flick; but within their narrow confines, the characters here--a grim cable-news anchor (Téa Leoni), her despondent mother (Vanessa Redgrave), a veteran astronaut (Robert Duvall)--effectively get us wondering how we'd react. The director, Mimi Leder, does a skillful if anonymous job of slamming the many subplots forward, managing to satisfy demolition junkies without capsizing the story's larger themes.

Larger themes--who are we kidding? All that matters in the disaster genre is mayhem. Maybe audiences would settle for still photographs when Henry Fonda pushed the button on Manhattan in Fail-Safe, but these days we want the computer-generated wrath of God, baby. Leder finally shrugs and gives everyone what they came for: a 1,000-foot breaker that crumples the Brooklyn Bridge, topples a World Trade Center tower, and drops the Statue of Liberty's head to the ocean floor (where Charlton Heston will presumably find it years later). Oddly, at the screening I attended, the audience did none of the cheering that accompanied the destruction in Independence Day. Maybe that's because Deep Impact does an unusually effective job of reminding us we're the ones being destroyed.