It won't make his publicists happy to hear it, but Sam Worthington is easily the biggest movie star in the world who wouldn't be recognized if he walked down a Manhattan street. Or if he climbed out onto the ledge of an East Side hotel and stood there for 100 minutes. Which is strange, considering that he was the star of the biggest movie in the world ("Avatar"), and the 160th biggest movie in the world ("Terminator Salvation"), and that he appeared last year in a mixed bag of features that included "The Debt," "Last Night" and "Texas Killing Fields."

But his Everyman-ish qualities serve him well in "Man on a Ledge," director Asger Leth's wryly twisted caper film. Mr. Worthington is a colossus of anonymity. "Man on a Ledge" is a movie that employs all the mechanics of a standard Hollywood thriller, while taking sidelong glances at the same voyeurism that fuels both the film and cinema itself. It's not "Rear Window": The ending, for instance, is so ridiculously tidy it squeaks. But en route to its kitchen-sink climax, "Man" manages to both amuse and provoke, to cleave to convention and promote ideas. And it isn't in 3-D. Theaters may want to consider charging triple admission.

We meet Mr. Worthington's Nick Cassidy as he emerges from the subway at Sixth Avenue, crosses a city abuzz with anonymous life, checks into a room at the matronly Roosevelt Hotel and eats the greater part of a mediocre meal. He then wipes down every surface he's touched and climbs out the window. It isn't long before he's spotted by the crowd on Madison Avenue, and not much longer before police detectives, including the acerbic Jack Dougherty (Ed Burns), realize that there isn't a fingerprint in the room by which to identify their would-be leaper. And that this is no ordinary suicide attempt.

It's just a theory, of course, but the sign of a worthy thriller may be how eagerly you want to revisit it, just to see where you went wrong—or where the movie did, in timing its narrative twists and "aha!" moments, and in providing sufficient information that one doesn't feel hoodwinked by holes in the plot. "Man on a Ledge" takes its sweet time explaining Nick's problem, and his intended solution, doling out relevant details like state secrets. But the structure seems sound, and it isn't giving anything away to disclose what viewers almost immediately learn via flashback: That Nick was an ex-cop serving 25-years at Sing Sing, where he fought with other inmates and revealed to the prison psychiatrist that, yes, he thinks about killing himself all the time. What follows is a hair-raising escape involving an SUV and a freight train, after which Nick concocts the grand design that brings him 200 feet above midtown.

Mr. Leth, the son of renowned Danish documentarian Jorgen Leth, has directed only one other film, "Ghosts of Cité Soleil," a highly stylized doc that revealed a soul yearning to breathe free of nonfiction. He has an instinct for weaving sturdy narrative fabric out of intersecting plot lines: While Nick keeps the city gawking, his brother, Joey (Jamie Bell), and Joey's girlfriend, Angie (Genesis Rodriguez), are busy breaking into the building across the street, owned by evil real-estate titan David Englander (Ed Harris). The police suicide specialist called to the scene, Lydia (Elizabeth Banks) has her own set of problems: She recently failed to talk another ex-cop off the Brooklyn Bridge, so she's dubbed "the grim reaper" by her less-enlightened colleagues. Meanwhile, Nick's old partner, Mike (Anthony Mackie), knows the whole story behind the stunt going on, up above. So we're watching the enormously talented Mr. Mackie even more intently than usual.

Amid the hoopla, Mr. Leth takes sobering assessment of media-circuses and mob mentalities: The people down below taking cellphone pictures, the ones yelling "Jump!"; the callous nature of cops for whom it's all routine. There's the occasional goofy grace note: Kyra Sedgwick, playing a voracious and obviously Anglo television reporter named Suzie Morales, rolls the 'R' in her surname as she signs off, just in case someone missed the point (we've all heard it). In another scene, Mr. Leth takes such pains to strip the shapely Ms. Rodriguez down to her underwear that audiences, who may well be leering, will also be laughing at how obvious it is.

There is a lot to forgive, it must be said: Myriad coincidences, a ridiculous helicopter scene, cops taking hip-shots throughout the hallways of the Roosevelt Hotel. But there are deft touches, too: When Lydia orders Jack out of the hotel so she can talk privately to the man on the ledge, Mr. Burns's voice jumps up an octave, just as it might, if the man behind it felt threatened by a woman. It's the kind of parenthetical subtlety one doesn't expect from many mainstream movies, but especially one working so hard for exclamation points.