Currently available in theaters: "Unstoppable"

The thrill of Tony Scott’s Unstoppable, in which a runaway freight train hurtles through rural — and toward not-so-rural — Pennsylvania, is that its setup asks us to believe only in human ineptitude. There are no scheming terrorists, no lone crazies: Just one numbnuts who decides to jump from the engine he’s driving, fully intending to jump back in before the thing really gets going. No one in Unstoppable actually wants this train — which happens, by the way, to be loaded with hazardous substances — to wreak havoc on the countryside and its attendant population. But everyone, including the moron who set the thing on autopilot in the first place, wants to stop it.

No one wants to stop it more than Frank Barnes (Denzel Washington), a longtime engineer who on this particular day finds himself stuck baby-sitting a rookie conductor, Will Colson (Chris Pine). These two aren’t, at first, anywhere near the runaway train — they’re driving another one that’s headed straight for it, on the same track — which gives them some time to work through the inevitable getting-to-know-you portion of Unstoppable. Frank has two almost-20 daughters whom he clearly loves very much — at the beginning of his shift, he hangs a photo strip of the two of them in his cab. (A moment of minor hilarity ensues when it’s revealed that both girls are waitressing their way through college — at Hooters.) Will is estranged from his wife and child as the result, we learn, of a misunderstanding; he spends much of his workday morning (too much, Frank seems to think) on his cell phone, trying to work out his myriad personal problems.

Washington and Pine are predictably likable, together and separately: Washington is wonderful at playing a great tease, and Pine’s grouchy, troubled character is eminently teasable. But what about that out-of-control train? Eventually, Will and Frank learn it’s headed their way, and Frank — working via radio with a no-nonsense yardmaster, played by the as-always marvelously expressive Rosario Dawson — hatches a plan that just might slow down the speeding behemoth. Or it might just kill him and his colleague. But in true Denzel Washington fashion, he’s just got to try it.

Unstoppable was inspired by true events — the script is by Mark Bomback, the writer behind Race to Witch Mountain and Live Free or Die Hard — and although many of the plot details seem plenty jacked up, it’s easy enough to believe that something like this could possibly happen. Of course, we’re in Tony Scott territory, so the runaway train just has to be carrying highly toxic gluemaking supplies. There’s also some folderol with a trainful of boisterous schoolchildren who, of course, do not get creamed by the oncoming loco-locomotive.

But Scott doesn’t get hung up on those specific clichéd details — he and cinematographer Ben Seresin treat them with a wink and move on, devoting most of their energy to building not-so-subtle layers of tension and suspense. The movie’s last half is beautifully sustained — the action isn’t so much fast-paced as it is discreetly, marvelously taut. And while the camerawork and the cutting are, in some ways, action-movie typical — there’s lots of zig-zaggy editing and clever, oblique camera angles — Seresin doesn’t just go for the obvious. As Frank and Will begin their workday, the engine they’re driving makes its way around an elevated curve of track in Stanton, Pa., and Seresin makes the landscape look dewy and gleaming in the morning light. He sees beauty in the surrounding working-class clapboard houses and old brick industrial buildings. This isn’t one of those “Why would you wanna live in this crap town?” visual essays; it’s more of a casual postcard with some real affection for the American landscape.

Even the unmanned train itself — it goes by the jazzy number 777 — has a personality of its own. Seresin and Scott are fond of showing it head-on, a red-faced beast with slanted windows staring us down like a pair of menacing eyes. If this were a Stephen King story, the 777 would have an evil heart and an even more evil mission. As it is, though, it’s just a powerful machine that has been let down by human dorkiness. The people who want to stop it include a know-it-all inspector (played, wonderfully, by Kevin Corrigan) whose unabashedly nerdy pronouncements grease the works with just the right amount of comic relief. “Will the portable derailing whichamajigger succeed in halting the train, thus preventing what could be the greatest railway disaster in history?” one character might ask him, to which he’ll reply, after a deep and thoughtful pause, “Possibly.” There’s no surefire cure for a runaway train. Plus this one is, as one character puts it, a missile the size of the Chrysler Building. It’s a thing of majesty and menace, just like the movie around it. Unstoppable is one gleaming machine paying tribute to another.