The premise of Man on a Ledge is not very likely when it starts, and it only gets progressively less likely the further it goes until it reaches an ending that might as well have been written for a fantasy novel. This might not have been a problem had the filmmakers gone all out and made it an escapist spy thriller – say, something along the lines of James Bond. Unfortunately, it was clear to me that they were taking this material seriously, and they actually expected audiences to do the same. This applies, oddly enough, to moments of levity so glaringly out of place that even listening to them is downright embarrassing. In a movie like this, you can’t convincingly lighten a tense and dramatic moment, especially when the dialogue is such that it wouldn’t pass muster in a second-rate romantic comedy.

The film stars Sam Worthington, who’s a decent enough actor but probably shouldn’t be relied upon for American roles. He’s not the best at faking the accent it requires; his natural Australian voice will repeatedly surface throughout the film, which only makes his character sound odd. He plays Nick Cassedy, who begins the film by checking himself into a room at New York’s Roosevelt Hotel, eating a meal, wiping everything he touched to remove fingerprints, writing a brief note, opening the window, and stepping out onto a narrow ledge. We then jump back in time one month, at which point we learn that he escaped incarceration at Sing Sing when he was allowed to attend his father’s funeral. We also learn that he was at one time a cop, adding even more intrigue.

Back to what I think is the present. A sizeable crowd has gathered at the intersection below, causing gridlock and street closures. The police have gotten involved and attempt to negotiate. As it turns out, there’s only one person Nick is willing to speak to. Here enters Lydia Mercer (Elizabeth Banks), a professional negotiator who, after failing to talk a cop out of jumping off a bridge, has lost the respect of her peers. At this point, we learn that Nick was imprisoned for stealing a large diamond; he’s now on the ledge in a desperate attempt to prove his innocence. He claims that he was set up by the diamond’s owner, a powerful tycoon named David Englander (Ed Harris), a vile and shallow corporate typecast. Lydia initially doesn’t believe Nick, although the more he talks, the more convincing he sounds. Is it possible that he’s telling her the truth?

Meanwhile, Nick’s brother, Joey (Jamie Bell), and his girlfriend, Angie (Genesis Rodriguez), have infiltrated the building across the street. Their assignment: Break into Englander’s vault and find the diamond. At their disposal are all manner of elaborate gadgets and gizmos, and of course, they will have to have crawl through air ducts, descend into rooms on cables, sidestep surveillance cameras and heat detectors, cut wires attached to alarms, and drill through metal doors. Why the filmmakers felt the need to make part of this story a Mission: Impossible rip off, I have no idea. It probably wouldn’t have been so bad had Joey and Angie not been reduced to comedy relief; they repeatedly argue and make flippant comments like a married couple in a badly written sitcom. Only in a movie like this could something so inane be crossed with a jewel heist.

Other characters work their way into the story, playing their contrived parts. There’s Nick’s former partner and friend, Mike Ackerman (Anthony Mackie). There’s Jack Dougherty (Edward Burns), an obnoxious detective who does little more than push Lydia’s buttons, even when he starts to take her seriously. And then there’s Nathan Marcus (Titus Welliver), who has the tough-talking New York cop stereotype down to a tee. The single most unnecessary character is a scoop-hungry news reporter who, despite being white and blonde, is named Suzie Morales – with heavy Hispanic emphasis on her last name. The fact that she’s played by Kyra Sedgwick doesn’t shed any light on the issue.

I suspect the plot wasn’t intended to get more and more ridiculous as it plays out, but that’s exactly what happens. The final quarter features two twists, one of which was expected due to the conventions movies like this operate under. The other was a genuine surprise, which isn’t to say it was effective; it’s a turn of events so arbitrary and nonsensical that I’m wondering if it was shot during post production and spliced in at the eleventh hour. But the greatest offense of Man on a Ledge was its very unflattering depiction of New Yorkers, who actively encourage Nick to jump and salivate greedily when Nick makes it rain money. The comparisons to Dog Day Afternoon become unavoidable when one of the onlookers, disgusted by the oppression of the everyman, actually starts chanting, “Attica! Attica!”