Furiously written on a typewriter over a three-week long creative binge in 1951, Jack Kerouac's On the Road is the seminal portrayal of "Beat" culture and its spiritual quest for expression.

The film version from Brazilian director Walter Salles ("Motorcycle Diaries") strives to capture the energy and drug-fuelled stream of consciousness of the original book.

Salles is helped by the casting of British actor Sam Riley as protagonist Sal Paradise, a stand-in for Kerouac himself, and U.S. actor Garrett Hedlund as Dean Moriarty, a symbol of American virility and poster child for living in the moment.

"The only people who interest me are the mad ones," Paradise writes, and Moriarty fits the bill. The charming, adventurous con man becomes Paradise's alter ego, and their closely bonded friendship plays out across a series of road trips.

"It's about the loss of innocence, it's about the search for that last frontier they'll never find," Salles told reporters in Cannes. "It's about also discovering that this is the end of the road and the end of the American dream."

Kristen Stewart of "Twilight" fame plays Moriarty's young wife Marylou, Kirsten Dunst plays second wife Camille and Viggo Mortensen takes a turn as Old Bull Lee, who is based on William Burroughs.

Salles said he and the team had "enormous respect for Kerouac" which helped drive the process from the time Francis Ford Coppola bought the film rights to the book in 1979.

The idea of making On the Road into a movie languished "until Walter raised his hand and said I think I can make this movie," said Coppola's son, Roman, who is a co-producer. "It took 30 years but it was such a natural fit with Walter."

Most early reviews were negative.

"It feels long and tedious, as if we've dropped in on someone else's party without knowing or caring who these folks are, knocking back the whisky and barbiturates as regularly as they're knocking off each other," wrote London magazine Time Out's Dave Calhoun.

British newspaper The Telegraph called the film a "tedious loop of beatnik debauchery" while the Evening Standard said it "seems to lack the mad passion of Jack Kerouac's ferocious and extraordinary writing."

ROAD MOVIE

Drugs, sex and jazz are central to On the Road, as the lead characters' quest for freedom of body and mind take them to black jazz clubs, flop houses, migrant camps and rail depots.

"A road movie I think is what made me into a film maker and I'm very loyal to it," Salles told the press.

He said he found parallels between Kerouac's search for inspiration through jazz and bebop as he wrote his novel in an improvisational style and the job of the director.

"You always have to be on the lookout for what you find along the way, it's a way of creating fantastic images."

Salles' camera captures America's vastness - and the promise of something new around the corner - from the lights of New York to the hills of San Francisco and the long expanse of flat road and endless sky in between.

But as the sun fades on the brief and bright explosion of the characters' lives, age and responsibility intrude.

"This high we're on is a mirage," character Carlo Marx tells Paradise and Moriarty.

For a look at Cannes' 2012 lineup, click here: link.reuters.com/vav28s

(Reporting By Alexandria Sage, editing by Paul Casciato)

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