Of all the movies made about America's experience in Indochina, "The Killing Fields" is the simplest and most serious and, because the truths of war tend to be simple and serious, the best. Telling the story of an actual American journalist and his Cambodian assistant who become friends against the backdrop of the "sideshow" war in Cambodia, the movie's never quite up to its material; the British writer, director and producer come as foreigners to someone else's story. But "The Killing Fields' " inherent scope and power, while daunting to its creators, also made it glitch-proof, a visually arresting epic guaranteed to capture the hearts and minds of its audience.

"The Killing Fields" is based on an article by Sydney Schanberg, now a columnist for The New York Times, recounting his experiences as a correspondent in Cambodia from 1972 through the fall of the Lon Nol government in 1975; the article focused on the tortures incurred by Dith Pran, Schanberg's friend and liaison during those years, when he was trapped in Cambodia during the wholesale butchery and dislocation that ensued.

For the most part, "The Killing Fields" is faithful to history, departing from actual events only occasionally to enhance the narrative. When Schanberg (Sam Waterston) arrives in Phnom Penh, he's met by Pran (Dr. Haing S. Ngor), who becomes his interpreter, wheel greaser and general factotum. Along with a freelance photographer, Al Rockoff (John Malkovich), and the rest of the foreign press corps, they hang out in a capital where bombs explode as routinely as flashbulbs. Alert to rumors of the accidental destruction of a nearby town by an errant B52 (a snafu denied by the American military attache'), Pran bribes a Cambodian patrol boat crew and the pair heads upriver.

Director Roland Joffe' doesn't turn away from the horror -- Schanberg and Pran discover an inferno of amputated limbs and infants who appear to have been roasted, of ruble and ruin, with the added irony that the victims turn to the reporter, as an American, for help, never realizing that Americans had done this to them. But to its credit, "The Killing Fields" is similarly unsparing of Schanberg himself. As he whines to the military attache', you realize that what's really important to the Timesman is getting the story. He's as disengaged from the suffering as the other Americans he criticizes.

"The Killing Fields" is the best movie about journalism since "All the President's Men," re-creating with an understated ease the atmosphere of the poolside bonhomie of the correspondents, the mechanics of getting and filing a story, and the moral quandaries of a reporter's professional detachment. This ambiance is more than mere texture, for the source of Pran's tragic odyssey lies in his simple ambition to be a reporter himself. When the government falls and the Americans bail out, Schanberg offers to arrange for Pran's evacuation; he refuses, partly out of friendship (he knows the American, something of a clod, would last about a minute in this foreign land without him), but mostly because he's a journalist, and journalists don't leave a good story.

The communists occupy the capital, and the chaos begins; Joffe', whose previous work has been in theater and television, manages these sequences with a hair-trigger feel for suspense. Schanberg, Pran and the other reporters are treated to a view of an execution, an insidious game of bobbing for an apple on the end of a bayonet in which, when the player bobs, he's shot through the head. The implication is that they're next, but the resourceful Pran wheedles for their freedom. Schanberg and Rockoff, however, prove less resourceful -- they bungle their attempt to forge a European passport for Pran. Like almost all other Cambodians, he must remain in the "killing fields," the name the Cambodians gave to the countryside in which, from murder and starvation, 3 million Cambodians (out of a population of 7 million) would lose their lives in a vicious spree of ideology gone amok.

The movie then crosscuts between New York and Cambodia, as Pran toils in a "reeducation camp" while Schanberg, back at The Times, collects prizes for his reporting and furiously contacts relief organizations and reporters in the Far East, in search of Pran. The movie starts to lose its footing here, as we watch Schanberg being chastised in a men's room by Rockoff for not doing more to help Pran, or punishing himself by watching highlights of the Nixon era on his Betamax while opera blares in the background. Who cares about Schanberg's guilt?

Waterston has created a wonderful portrait of a Schanberg who is a pallid, petulant phony, a top-of-his-class martinet (when, hands on hips, he informs the Cambodians holding him under house arrest that he's going to leave and file his story, he might have added "Nyah nyah nyah nyaaaayh nyah!"). But Waterston's performance cuts against the emphasis Joffe' wants to give Schanberg; the reporter's guilt seems like a pose -- it doesn't have any weight. The way this scene shifting tries to equate Schanberg's suffering with Pran's is hyperbolically distasteful (it's one thing to feel guilty, another to be coshed with a rifle butt); and the way the movie implicitly likens what Schanberg has done to Pran with what America has done to Cambodia stretches things a little.

Making Schanberg the center of "The Killing Fields" is screenwriter Bruce Robinson's particular blunder, for the story is rightfully Pran's. The sequences that follow Pran's sufferings in the forced labor camps and his escape are the most powerful in the movie. Daringly, Joffe' shoots them in Cambodian, without subtitles -- the incomprehensibility of the language unmoors you, so the scenes feel as frightening as they do for Pran. Pran becomes gaunt and malnourished in these holocaust sites where "only the silent survive" (those who admit to education, or knowledge of foreign languages, are summarily executed); maddened by starvation, he slits the flank of a cow and sucks its blood, like a horsefly, and when he's caught, the guards beat him silly and tether him to a tree to await his fate. Making his escape, he falls into a mass grave piled with skeletons that stretches to the horizon.

Such scenes take place in silhouette against the staggering beauty of the Cambodian (actually, Thai) landscape, greens and sunset-oranges that almost fluoresce. Chris Menges' cinematography is vividly stylized, both in these scenes and the earlier crowd scenes: the camera jogs back and forth, as one character and then another takes the center of the frame, becoming a metaphor for "The Killing Fields' " theme of how individual lives unfold amid the chaos of the million. Like Mike Oldfield's piping, Philip Glassian score, Menges' compositions have a haunting, otherworldly beauty, a counterpoint of nature and nastiness.

As Pran, Ngor is the most retiring of screen presences. He's utterly blank through most of the movie, so when he chooses to emote, it detonates; when Schanberg tells him they've botched the forged passport, he withdraws in a little nauseous hitch-step, clutching his stomach -- a heart-wrenching snapshot of despair. Crisscrossed with camera straps, his eyes hidden by tea shades, Malkovich finds the low key of lunacy; his whispery delivery provides a balance to the flamboyant craziness of his lines. These lead players are joined by a uniformly brilliant supporting cast, particularly Scottish actor Bill Paterson as a surgeon struggling with the carnage and avant-garde monologuist Spalding Gray as an American foreign service officer bothered by his conscience.

Perhaps because the Britishers who made "The Killing Fields" got their story secondhand, they're inclined to add a discordant dram of moralism: this journey into the lower depths ends with the namby-pamby fatuity of John Lennon's "Imagine." That's not what this story is about at all -- after watching a people whom Americans had devastated finally throw the foreigners out, only to set about murdering each other, these reedy maunderings about "no country," "no possessions" and "no religion" seem perversely idiotic (indeed, Pran's Buddhism and his patriotism were the keys to his personality, and his survival). You don't leave the theater humming along, but with your head humming, as the painful images of the waste of war refuse to go away.