A new Kingfish.

IN the movies, succeeding in politics is simple: You just need to take on the special interests, promise the world to the poor, and give a really stirring speech. Which means that Huey Long, the outsize Depression-era governor of Louisiana, was born for celluloid, since he actually governed that way--by elevating political theater to an art form, and using a noisy populism to run roughshod over the normal checks and balances of American government.

Playing Long--or rather, Willie Stark, Robert Penn Warren's fictionalized Kingfish--in Steven Zaillian's ponderous adaptation of All the King's Men, Sean Penn seems to be having as much fun as he's had in his entire career. (Though maybe not as much fun as the real Long; this was a politician, after all, who founded his own newspaper when he didn't like his press coverage, ran on a slogan of "Every Man a King," and managed to get himself elected both U.S. senator and governor at the same time.) Having earned his "Brando for our time" reputation with forehead-furrowing downers like Mystic River, Penn seems liberated by the chance to play a caricature. He sports a paunch and a twinkle in his eye, and he flips his hands around in an odd, almost bird-like way while he delivers his hell-raising speeches, as though demagoguing were a form of ballet. Robert Penn Warren burdened his antihero with a quasi-Biblical patter, part Faulkner and part cornpone, but Penn sells the Starkisms--"Man is conceived in sin and born of corruption, and he passes from the stink of the didie to the stench of the shroud"--as though they were Shakespeare.

This is an actor's stunt, perhaps, rather than a great performance, but most successful politicians are more ham than Hamlet, and the fact that Penn's scenery-chewing lacks real depth doesn't detract from the fascination of watching his Willie Stark at work. So long as Penn is center stage, All the King's Men crackles with life, and you can ignore the various annoyances--the dumbed-down moral dilemmas, the cast of all-stars who were all apparently too important to learn a southern accent, and the delusion of seriousness that broods over the whole affair.

Which means, in turn, that you should consider walking out midway through. In the half of the movie that covers Stark's rise to power, the various supporting players orbit his brilliance without eclipsing it--Jude Law's Jack Burden, the old-money heir turned cynical newspaperman, who is attracted to the self-proclaimed "hick" candidate in spite of himself; James Gandolfini's Tiny Duffy, the political boss who sets out to use Stark and ends up as his henchman; Anthony Hopkins's courtly Judge Irwin, the establishment pillar (and a father figure to Burden) who eventually becomes Stark's most obdurate opponent. But once Stark is ensconced in the governor's office, taking on the fat cats while acquiring a taste for corruption himself, the movie turns its focus to Burden--to his patrician melancholy, his tedious crises of conscience, and the sorrows of his past. From that point on, All the King's Men descends into Gothic hokum: old oaks and decaying mansions, suicides and swamp rot, set to a thudding, portentous score.

Stark asks Burden to dig up enough dirt to blackmail Judge Irwin, and he reluctantly agrees; meanwhile, two of Burden's childhood friends, the Stanton siblings, re-enter his life, setting in motion a convoluted series of betrayals that ends in murder. It's all very tragic, or it would be if Kate Winslet and Mark Ruffalo--as Anne Stanton, Burden's lost love, and her idealistic doctor brother--didn't seem so dazed and disinterested, so overcome by the delta heat, or perhaps their underwritten roles. They've all been traumatized, we're given to understand, by some long-ago tragedy--but then the crucial flashback rolls around, and it turns out to involve Law and Winslet losing a chance at some premarital nookie. (The film plays this scene like Aeschylus, and you would need a heart of stone not to giggle.)

And Jude Law--what in God's name has happened to Jude Law? When he burst into movies a decade ago, playing a crippled, furious genetic superman in Gattaca, and then Dickie Greenleaf, the murdered golden boy in The Talented Mr. Ripley, he seemed like a throwback to an earlier era, when Hollywood stardom required an actor to be dazzling and deadly all at once. But the hint of danger he brought to those early roles has evaporated, leaving a callow charm that might seduce a giddy woman, but not an audience. He's not terrible as Burden, and his accent is mildly more believable than Hopkins's clipped Welshisms, or Gandolfini's Sopranofied drawl. But neither is he interesting: In a part that asks him to play a man beset by private demons, his beauty is like a thick layer of ice on a pond, reflecting the sunlight and hiding everything underneath.

Eventually, the movie finds its way back to Penn's Stark, fighting off impeachment, and then to a denouement in the gorgeous art-deco Louisiana State House, where all the strands of blackmail and betrayal are drawn together. But the Kingfish has been neglected for too long, and the movie's life has ebbed away long before the guns go off and the blood begins to flow. Worse, the film never even gets around to deciding just how corrupt Willie Stark really is, preferring to wallow in aristocratic misery while the hard questions--is wickedness worth doing for a greater good? where does compromise shade into complicity, and redistribution into pillage?--go unanswered.

Such avoidance of real politics is the natural drift of all political cinema: The camera is an anti-democratic instrument, in a sense, built for rhetoric and propaganda, restless once the cheering stops. So it is that after all the shouting and the shooting, but before the credits roll, All the King's Men flashes back to Stark on the stump, roaring and ranting and promising a better future to the working man. It should all be so simple, the parting shot suggests. But that way lies fascism, or at least Huey Long's Louisiana.