A fun tone is undermined by disjointed storytelling in George Clooney's "The Men Who Stare at Goats," and it all starts with the disclaimer that opens the movie: "More of this is true than what you might imagine."

This wry comment serves as a nod and a wink from the filmmakers, a license to do what they will to Jon Ronson's amusing nonfiction account of the U.S. military's hush-hush research into psychic warfare and espionage.

What Clooney's producing partner, first-time director Grant Heslov, and his colleagues come up with is a hit-and-miss fictional narrative on which to string some of the brightest anecdotes Ronson uncovered about efforts to create warrior monks who try to walk through walls or glare animals to death.

The priceless opening scene - recreating the start of Ronson's book as a general attempts to displace his molecules and run through his office wall - promises a Catch-22 or Strangelove-style satire.

But the book is a loosely connected journey from one absurdity to the next, sprouting offshoots and asides, great stand-alone burlesques and dramas that don't lend themselves to a cohesive film.

The dramatic spine developed by screenwriter Peter Straughan jettisons much of the book's darkest and most-compelling moments - a CIA murder plot, psychic warfare links to the Branch Davidians and the Heaven's Gate cult suicides - in favour of a gag-laden jaunt stretching from Vietnam through the war on terror.

Delivered with goofy gusto by Clooney and co-stars Jeff Bridges, Ewan McGregor and Kevin Spacey, "Goats" is fitful, undemanding, and ultimately lightweight humour.

Something of a stand-in for Ronson, McGregor's Bob Wilton is a reporter who stumbles onto the story of the New Earth Army, founded by Vietnam vet Bill Django (Bridges), the pioneer of New Age techniques meant to give his troops a spiritual edge and superpowers to win over enemies - or wipe them out.

Django's prize pupil is Lyn Cassady (Clooney), whom Wilton accompanies through a series of mishaps on a mission in Iraq.

Inspired by real people Ronson encountered, Cassady and Django have the scent of authenticity about them. Not so with Wilton and his awkward, ill-defined motivations for uncovering the story, or with Spacey's Larry Hooper, a psychic rival to Cassady who's a stiff contrivance meant to add tension.

The fictional plot line isn't terribly interesting, though it's nicely ornamented by little farces lifted from the book - a guy convinced that the Loch Ness monster is the ghost of a dinosaur, another who advises that Angela Lansbury somehow knows the whereabouts of Manuel Noriega (it was Kristy McNichol in the book, but same chuckle nonetheless).

The actors carry baggage that creates some unfortunate distractions. Clooney at times seems like a cross between his Desert Storm operator from "Three Kings" and his loony-tunes Odysseus from "O Brother, Where Art Thou?" Django plays a bit like Bridges' Dude from "The Big Lebowski" had he joined the Marines.

McGregor's "Star Wars" connection proves jarring as the film incorporates Ronson's references to psychic warriors as Jedi knights. It's cute once, but the repeated Jedi-speak in the presence of Obi-Wan himself grows tiresome.

In fits and starts, director Heslov captures a lot of the drolly incredulous spirit of the book. It's just too bad the dots don't connect better.