The post-Cold War epoch hasn’t been all that kind to John Le Carre. The novelist’s specialization in Soviet-era spycraft had served him well: his George Smiley books were classics of their time, not just icily precise in their delineation of the atmosphere of the period but equally acute in characterization. (They were also beautifully adapted in miniseries form, with Alec Guinness superb as Smiley.) And while his other pre-1991 books weren’t up to that exalted standard, they still were the class of the genre. But the novels Le Carre has written more recently haven’t had the same cool intensity and air of detached gamesmanship; they’re grown looser, more inclined to pontificate, more obvious in their effects. Nonetheless even they are more controlled and cerebral that other books of their kind, and it remains difficult to capture their idiosyncratic tone on film.

“The Constant Gardener” is typical of Le Carre’s most recent work in that it’s angrier and more polemical than his writing used to be, though the prose itself retains a goodly measure of the old lordly elegance. It’s about Justin Quayle, a middle-aged, sedate mid-level British foreign service officer in Kenya who investigates the brutal killing of his much younger wife Tessa, an idealistic activist murdered while on a humanitarian mission in the wild with an African doctor rumored to have been her lover. The effort to unravel the mystery behind her death leads Justin into the darkest realities of the western exploitation of the continent, revealing deception and collusion between governments officials, both local and foreign, and giant multinational pharmaceutical corporations. It also, ironically, brings him a deeper understanding of, and love for, his wife than he’d had while she was alive, engendering in him the same sort of passion for the truth and hatred of duplicity that had driven her while he’d been content to sit quietly on the sidelines. In effect, he takes up her cause, becoming as much a thorn in the side of the establishment as she was.

Screenwriter Jeffrey Caine has adapted Le Carre’s narrative quite faithfully. Certainly he’s retained the book’s underlying vitriol at capitalist exploitation of Africans. He had to simplify Quayle’s labyrinthine investigation, of course, which in the novel involves reams of documents and computer records that would have been deadly to wade through on film. And he’s added an audience-pleasing penultimate episode that undermines the author’s far more cynical stance and panders to today’s cinematic expectations. But the scene that will perhaps strike you as the crudest thriller element–in which Quayle is assaulted by mysterious assailants when he’s getting too close–is actually taken directly from the book, where it seems one of Le Carre’s most notable miscalculations. Overall, however, Caine has done a serviceable job. The central problem is that as constructed by Le Carre, the piece isn’t very suspenseful, and so the adaptation isn’t, either. You’re likely to have figured out what’s going on long before Quayle does. As a result whatever power the film possesses has to come from the execution, and here there are significant drawbacks. Ralph Fiennes does the soulful, little-man-reaching-new-heights business well enough, but frankly we’ve seen his quivering lip and muted rage too often in the past to be much impressed by it here. And Danny Huston telegraphs the sinister character of Quayle’s colleague Sandy Woodrow too insistently. But the major casting blunder is Rachel Weisz’s Tessa, which never convinces. In the book the age difference between Justin and his wife was far greater, but lessening it isn’t the central problem; it’s that Weisz comes on too strong. There are ways of registering passionate commitment without becoming irritating, but Weisz doesn’t manage it. On the other hand, Bill Nighy exudes the oily self-confidence appropriate to Pellegrin, the FO head, and Pete Postlethwaite is agreeably energetic as Lorbeer, the mysterious doctor who shows up in the last act.

But the acting isn’t the only part of the execution that’s problematic. The direction of Fernando Meirelles is also troublesome. One has to appreciate the care with which he’s modulated the tempo of the film: the first act is presented in a cool, stately fashion, but as the narrative kicks in he jump starts the rhythm, gradually moving into the hyperkinetic, jaggedly-edited, hand-held style he employed so effectively in “City of God.” It’s doubtful, though, that this edgier, gaudier approach (abetted, of course, by Claire Simpson’s cutting and cinematography by Cesar Charlone that gives the Kenyan locations the same sort of blinding color scheme that marked the earlier film) is really much suited to an adaptation of Le Carre’s book. It certainly gives the latter portion of the picture a visceral energy, but the flamboyance seems at odds with the original, which, like Quayle, retains its customary surface poise through the very end. The clash between style and substance grows stronger and stronger as the film proceeds.

One has to admire the craftsmanship and serious intent behind “The Constant Gardener.” But in the end it not only preserves the book’s flaws but has added to them. As a cinematic effort to raise the issue of western malfeasance in dealing with African problems it’s an improvement on the lumbering, ultimately incoherent “The Interpreter,” but as is so often the case, the combination of drama and soap box proves an uneasy, and ultimately unsuccessful, one.