For around two-thirds of this film, when I wasn't enraptured by the plot's labyrinthine structure, I was composing sound bites for my review. A taut political thriller. A top-notch nail-biter. Etc. And while it slips toward the end, losing some of those glowing, ready-made compliments, it is still a satisfying thriller: smart, mostly believable, and respectful of the intelligence of its audience. It's not a Great Thriller, but it's a more than welcome diversion, and a great way to spend a Saturday afternoon.

This was the first film to be shot at the United Nations; I was surprised at how ugly the actual building is. Anyway, Nicole Kidman plays Silvia Broome, an interpreter who, late one evening, overhears a conversation between two men; speaking in a language that only she and a small handful of people in the United States could understand, they discuss what sounds like an assassination attempt on a a controversial African leader, who is due to speak at the UN the following week. Dictator of the fictional country of Matombo (but likely based on Robert Mugabe of Zimbabwe), Zuwanie (Earl Cameron) started off as a liberator but has turned to genocide. He's trying to avoid being brought before the International Criminal Court, and he thinks that a speech before the UN about how much he's changed will save him.

Sean Penn and Catherine Keener play two members of the Secret Service's diplomat protection unit; their job is to assess the situation, figure out how much of a threat there really is, and deal with it. Penn plays Tobin Keller, who is attempting to deal with the recent death of his wife by throwing himself into his work. He instinctively distrusts Silvia, especially after it turns out that she's from Matobo, her family was killed by Zuwanie's mines, and her brother is involved in some kind of anti-Zuwanie activities. It doesn't help that she refuses to tell him the truth about anything. The dialog between Penn and Kidman is smart and often funny; she says at one point, "Let me be honest with you... I don't know how honest I can be with you." The script, by Charles Randolph, Scott Frank, and Steven Zaillian, is a treat to fans of thrillers because it isn't simply about expository dialog and pushing the plot forward. For the most part, characters sound believable as federal agents and UN employees and suchlike. Also helping with the believability is the fact that it was shot at the UN, and many of the extras wandering around are actual diplomats and attachés.

The tension builds through almost two-thirds of the film; it climaxes in a somewhat improbable scene where many of the major players find themselves on the same bus. If I sit down and think it through, it seems highly unlikely that things would have turned out the way they did. But there in the theater, I was literally on the edge of my seat, holding my breath and wondering how on earth it could possibly end well for anyone involved. Sadly, the film loses momentum after that point. I can't put my finger on it, but it seems to lose its relentless focus; a few too many coincidences build on one another, and it falls off its high-wire of believability. I don't want to get too involved in the details, but elements of Silvia's past emerge that would have made it highly unlikely that she would have ever gotten her UN interpreter job in the first place.

One of the biggest annoyances about the film is the lackluster job on photo editing. You know the kind: there's a photo where one of the actors has been pasted in, and the characters in the film act as if they can't tell it's been Photoshopped. The ones that crop up in this film are so amateurish—you can't even glance at them in passing and not know they've been modified—that at first I was sure that doubts about their authenticity was going to figure into the plot. But no, even the Secret Service in this film can't recognize a bad Photoshop job. (I guess that wouldn't count as a big annoyance for some people.)

Unlike your usual Jerry Bruckheimer–produced action spectacular, this film cares about its characters, and it seldom falls into any of the usual traps. There's obviously a spark between Penn and Kidman—both of them are intelligent, grieving people with quite a bit in common—but the film realizes that they've got more important things to do than have a soft-focus PG-13 sex scene. The political angle actually sounds plausible, as do the reactions of just about everybody involved. And there's one kick-ass suspense scene at the center of it all. I can't ask for a heck of a lot more from a thriller.