HOLLYWOOD'S APPROACH TO ADAPTING BOOKS recalls Karl Marx's much-quoted dictum that historical events occur first as tragedy, then as farce. Of course, John Ronson's The Men Who Stare at Goats was half-farce to begin with. But the British journalist's 2004 book also found considerable pathos in its account of 30-some years of U.S. dabbling in "psychic warfare." The people whose exploits Ronson reconstructed may never have killed a goat by staring at it — the evidence is equivocal — but some of them did murder people by more conventional means. And their experimental techniques for torture and mind control, mostly rejected by the U.S. military in the 1980s, made a big comeback after 9/11.

That's the hook for the film, which admits only to having been "inspired by the book." Because it's the story of not entirely getting the story, Ronson's account is told in the rueful first-person. The movie, however, invents a failed small-town journalist, Bob Wilton, and sends him to Iraq while the war rages. And since the soldiers Ronson chronicled sometimes referred to themselves as "Jedi warriors," the filmmakers cast as Wilton none other than Ewan MacGregor, who was totally unmemorable as the young Obi Wan Kenobi in those unnecessary second-generation Star Wars flicks. MacGregor's blank look whenever someone says "Jedi warrior" is a safe, if not especially hilarious, movie-buff in-joke.

Wilton flees Michigan after his wife — essentially the only woman in yet another of co-producer George Clooney's on-screen stag parties — dumps him. He lands in Kuwait without journalistic credentials, and happens to meet a former member of the New Earth Army, Lyn Cassady (the characteristically self-amused Clooney). Cassady says he's been reactivated, and he leads wimpy Wilton into Iraq because, he eventually explains, he intuits that the would-be war correspondent has latent psychic powers. After various misadventures, Wilton and Cassady join some of the latter's former colleagues, including new-age visionary Bill Django and the devious Larry Hooper. (They're played by, respectively, Jeff Bridges and Kevin Spacey, neither of whom deviates a millimeter from his customary onscreen trajectory.) In one of many jokes that Peter Straughan's script fumbles, the New Earthers are now private contractors for the U.S. military — in other words, Blackwater on peyote.

None of this is exactly in the book, which pursues the case of the defunct First Earth Battalion, and introduces such former members as Jim Channon, Lyn Buchanan, Glenn Wheaton, Albert Stubblebine, and Ed Dames, as well as a guy who claims he can stare hamsters to death. While Django is clearly based on Channon, and General Hopgood (Stephen Lang) is basically Stubblebine, the others are composite characters, or mostly fiction. Yet pieces of Ronson's report have been torn from its pages, sometimes at random, and inserted into the movie. ("More of this true than you might imagine," smirks an opening note.) One of the funnier bits, for example, is 100 percent Ronson: He recounts how, during Gulf War I, the Iraqis tried to undermine American morale with leaflets that warned, "Your wives are back at home having sex with Burt Reynolds and Bart Simpson."

Channon/Django has a new-age epiphany while fighting in Vietnam, where he realizes that most of his soldiers are not shooting to kill. (See the documentary Winter Soldier for a much grimmer account of how the Army reacted to this difficulty.) And so first-time director Grant Heslov, a Clooney crony and one of the film's co-producers, treats the story as a '60s flashback. He cues up the period pop-psychedelia — the Small Faces's "Itchycoo Park," a remake of the Electric Prunes's "I Had Too Much to Dream Last Night," as well as some Boston and Billy Idol — and builds to an LSD-fueled climax that's sort of Apocalypse Now lite. (There's even a Moody Blues joke.) Ronson's book, however, finally shifts in a very different direction: It culminates with the tale of Frank Olson, who was most likely murdered by the CIA — "collateral damage" from MK-ULTRA, the agency's experiment with LSD as a mind-control and interrogation aid.

That's too much of a downer for the movie, which trades in leftist outrage against the war in Iraq while trying not to take anything very seriously. Heslov and his collaborators even indulge a liberal revenge fantasy, in which some Iraqi prisoners are spontaneously released from the shipping-container cells in which they've been tortured. But the film prefers not to emphasize the more physical forms of abuse — for that, see Taxi to the Dark Side — and it certainly doesn't want viewers to ask if the men being set free are innocents who will go home to their families or fanatics who will return to killing American soldiers and Iraqi civilians. The movie prefers to focus on the fact that some of these prisoners had been tormented with endless rounds of insipid ditties from Barney and Sesame Street.

Everybody's in show-biz, as Ray Davies first sang a few years before Saigon fell, so Ronson's book anticipates Heslov's painstakingly shallow adaptation of it. Not only does the author note that Ed Dames negotiated with Hanna-Barbera to create a Saturday morning cartoon show about psychic soldiers, he also recounts how U.S. magazines and TV news programs treated torture by the Barney theme song as simply "a funny story for the people back home."

Which, of course, also describes this movie. Given its structure, first-person narrative, and four-decade sweep, The Men Who Stare at Goats is a difficult book to condense into a film. The tale is also a hard sell, despite its humorous absurdities, because it's littered with corpses. One of the victims was Frank Olson, whose son Eric laments the difficulty of interesting journalists in a story about MK-ULTRA that isn't crude and snickering. (Buttoned-down CIA spooks dispensed acid! Hee hee!) "The old story is so much fun," Eric says. "Why would anyone want to replace it with a story that's not fun?"

He's talking about the attitude of the mainstream news media. But he could just as easily be referring to the American movie biz.

THE MEN WHO STARE AT GOATS — 2009, 95 min; at most multiplexes.