What's gonna happen? Probably a fist-fight, Jack White, the frontman with rock duo the White Stripes, mutters from the back of his limousine.

Prisoners being led to their execution seem only slightly more nervous. But the guitarist awaits a fate for which most rock fans would sell their souls to the devil: a summit with axmen, Jimmy Page of Led Zeppelin and The Edge of U2.

The trio's private gathering on a Hollywood soundstage was filmed 18 months ago for a documentary, It Might Get Loud, which opens in New York and Los Angeles on Friday before rolling out across North America.

The film, from Oscar-winning director Davis Guggenheim (An Inconvenient Truth), focuses on the relationship each of the musicians has with his guitar. In individual segments, each returns to his youthful haunts, and fondly recall burgeoning love affairs with the tools of their trade.

The Edge walks the corridors of Mount Temple, the Dublin high school where U2 formed. In perhaps the film's most memorable scene, a grinning Page plays air guitar at his home as he listens to old Link Wray and Muddy Waters singles.

The three finally meet up for the aforementioned jam session, swapping war stories and trading licks on such tunes as Led Zeppelin's Whole Lotta Love and U2's I Will Follow.

SMACKDOWN?

Three different generations are represented. Englishman Page, 65, the slightly demonic blues appropriator who led the biggest band of the 1970s; Irishman the Edge, 48, the gadget-loving wizard in one of the biggest band of the last two decades; and American White, 34, a doggedly independent lo-fi adherent who is suspicious of modern technology.

Technology is a big destroyer of emotion and truth, White says at the outset of the film. That's the disease you have to fight in any creative field: Ease of use.

Cut to the Edge, almost lost in an electronic jungle of amplifiers, pedals and wires.

I'm very interested in what hardware can do to an electric guitar sound, he says. I love effects units. They've always pushed music forward.

It seems a smackdown is in the works, as Page sagely notes on his way to the jam session. It's going to be very interesting. Very, very interesting. Both are really, really strong character guitarists.

But all swear that the summit went off swimmingly.

We've all seen 'Hail! Hail! Rock 'n' Roll' and know probably it's not a good idea to turn Jimmy's amp down, White joked, referring to the tense rockumentary featuring Chuck Berry and his weary protege Keith Richards.

Guggenheim said the casting process was simple. Page, the Edge and White were the only guitarists considered, and they quickly signed on.

We weren't looking for three from different generations, we weren't even trying to cover any bases, Guggenheim said. We were just trying to find three really fascinating people who are still searching and still trying to tell their story.

SIMILAR SHADES OF BLUES

As it turns out, Page and White had plenty of common ground, a passion for the blues. And White, of course, was raised on Led Zeppelin.

They're the biggest explosive supernova that happened to the blues since Robert Johnson in the last hundred years, White told Reuters. No way to ignore it.

Page said he had not heard any of the White Stripes' dissonant, blues-punk music before he saw them perform with his former bandmate Jeff Beck in London, in 2006. But he quickly caught up and became a fan.

That left the Edge, whose band developed as rejection of white-boy blues bands, as a potential odd-man-out.

He was more au fait (with musical traditions) than possibly I thought he would have been, said Page.

Indeed, the Edge's manipulation of guitar tones left a positive impression on White, who will have to save his boxing gloves for another occasion.

But Page and White were cagey on whether the filmmaking experience would lead to additional collaborations such as a tour or album.

There's a lot of things we could do, said White, who already plays with two other side projects. I don't think any of us would do it just to do it, because it would make a splash. It has to have a context.