Sylvia Broome (Kidman) is a UN interpreter who grew up in Matobo, an African country that descended into terrifying dictatorship after colonial rule ended. When she overhears an apparent plot to assassinate the Matobo president (Cameron) on his impending visit to New York, she becomes the centre of a Secret Service investigation, tailed by Agent Keller (Penn), who's experienced almost as much tragedy as Silvia has. But as the body count grows, it gets more complicated to figure out who's behind this plot.

Pollack directs this impeccably, building tension subtly until it erupts with startling ferocity. And the dramatic plot elements are even stronger, as two people with different outlooks on life are forced to find common ground. The film has the look of a classic--slick and sharp, full of attitude and personality, with expert cinematography by Darius Khondji and a resonant James Newton Howard score. And Pollack makes the most of his unprecedented access to actually film within the United Nations.

Meanwhile, Kidman and Penn have an astonishing chemistry that ripples with tension and emotion. Their scenes are raw and powerful, and it's to the filmmakers' credit that their dialog is relatively limited, avoiding banal plot exposition in lieu of deepening character intrigue. Red herrings abound, everyone is suspect, and we really care! Meanwhile, Keener shines as Keller's acerbic partner, adding a nicely world-weary tone to remind us that these people are just doing their jobs.

This film is so full of superb touches (like Silvia's vintage Vespa) that we can forgive its one moment of weakness: an overwrought climactic scene that barely crosses the line into silly, moralistic moviemaking. But this is an expertly made, grippingly old fashioned thriller that keeps us guessing, and squirming right to the end. As Silvia says, "Words are slower than guns. But they're better."