The genius of The Constant Gardener is that its central question of suspense is not "What horrifying crimes against humanity are multinational corporations, in cahoots with governments around the world, committing this time?" That is a small part of the film's suspense, but only a small part, because, Duh, of course the powerful white men are up to something nefarious. The central question of suspense here is, "What is one not-so-powerful white man going to do about it?" Like The Insider, from a few years back, Gardener is a thriller of the conscience: It's easy to ignore all the awful, terrible things happening all around us all the time when you don't have to actually look at them; but when you're confronted with indisputable evidence, when the perfidy is right in front of you, what are you gonna do?

Russell Crowe found himself staring the deceit of tobacco companies in the face (duh: of course Big Tobacco knew about the dangers of smoking their cancer sticks but covered it up), but here Ralph Fiennes (The Good Thief, Maid in Manhattan) takes quite a while to open his willfully closed eyes. His Justin Quayle, a low-level British diplomat in Kenya, is basically us: He's got a good job and the respect of his colleagues at the embassy and a nice house with the garden out back he likes puttering around in: he's not gonna rock any boats. Which is, actually, according him more volition than he has, at first: he is completely ignorant of anything to rock any boats about; certainly he has no information about any malfeasance on the part of British pharmaceutical companies in the region... because he doesn't want to have that information. (Big pharma -- they're as bad as the arms dealers! an impassioned Pete Postlethwaite [Dark Water, The Shipping News] reminds us later. Duh.)

His wife, though, is a bit of a problem. Tessa (Rachel Weisz: Constantine, Runaway Jury) is something of a quaint hippie throwback, a professional troublemaker: Isn't it cute how she works with HIV-positive mothers in the slums of Nairobi, like she thinks she can actually make a difference? She's a problem for Justin's bosses, because she asks embarrassing questions at embassy cocktail parties of local warlords the Brits are romancing; but she's a bigger problem for Justin, because she rocks his complacency, forces him to open his eyes. Of course, they first met over a matter of some political urgency about which he was blasé and she was aflame -- something to do with Iraqi oil and an illegal war -- and the torrid chemistry between Fiennes and Weisz as they fall instantly into bed serves to suggest that some part of him was ready to discard his apathy and embrace anger. But not yet.

It takes, in fact, her death to begin to wake him up. (This happens quite early in the film, and spoils nothing to reveal; much of the story is occupied with flashbacks during which their contentious relationship unfurls.) She heads off on a factfinding mission and ends up dead by a roadside; the authorities suggest bandits or, perhaps, that she was having an affair with her coworker/fellow agitator (Hubert Koundé); later the film floats the chilling term "corporate murder," but, duh, you already knew that was the most likely explanation.

Oh, I suppose The Constant Gardener is a thriller, in some respects, but mostly it's a tragedy. For Justin, it's the tragedy of only coming to geniunely know and appreciate and even love his wife after she's gone, as he retraces her footsteps in a griefstricken effort to find out why she was killed and finds himself awakening to the reality she lived in, of corporate and government collusion in Very Bad Things, of poor, desperate people taken advantage of because they have no voice to protest such treatement with. And it's a tragedy for us, because we saw Tessa as quaint and outmoded and Justin as logical and reasonable when what the world urgently needs is the passion of more Tessas, when the remove of the Justins contributes to problems so enormous they seem unfixable.

We get there by the end, along with Justin, who once dismissed Tessa's efforts to Do Something with "There are millions of people -- they all need help" but comes to realize the immense value of helping just one of those millions. But as dynamic and alive as Fernando Meirelles's film is (it's not the revelation his City of God was, but it is the best of what big-budget, mainstream filmmaking can be), it is, ultimately, more despairing than hopeful. It is so elegantly plausible, in all its talk of paranoia, the surveillance society, and corporate/government conspiracies, that it leaves you laden with a sense of inevitability. Enraged you may well be by the end of The Constant Gardener; you're just as likely to wonder what any one person can possibly do in the face of what it delineates.