Early in "On the Road," Sal Paradise (Sam Riley) utters what might be the most famous phrase from the novel on which the film is based. Looking with awe at his crazy, cool, creative friends, he says the only people for them are "the mad ones, the ones who are mad to live, mad to talk, mad to be saved, desirous of everything at the same time, the ones that never yawn or say a commonplace thing, but burn, burn, burn like fabulous yellow roman candles exploding like spiders across the stars."

That partial line goes a ways toward capturing the spirit of Jack Kerouac's novel of discovery. Sadly, the first feature film adaptation of the 1957 book doesn't do quite so well. That's not to say director Walter Salles hasn't tried, and that he doesn't, now and then, succeed. But he pays too much attention to the sensation of the novel and not enough to the soul.

The book is about the closest thing to an autobiography a novel can be; Kerouac changed names and some details at his publishers' urging. Salles and his screenwriter, Jose Rivera, have made changes from the novel, adding in sexual detail, for example, that Kerouac couldn't include in the 1950s, as well as details from the lives of the writer and his well-known friends.

On screen
'On the Road'
» Rating: 2.5 out of 4 stars
» Starring: Sam Riley, Garrett Hedlund, Kristen Stewart
» Director: Walter Salles
» Rated: R for strong sexual content, drug use, and language
» Running time: 125 minutes

The friend who inspired "On the Road" was Neal Cassady, called Dean Moriarty in the film. Sal meets Dean (Garrett Hedlund) when he and Carlo Marx (Tom Sturridge plays the Allen Ginsberg stand-in) show up at his apartment soon after Dean and his new wife, 16-year-old Marylou (Kristen Stewart) arrive in New York. Dean opens the bedroom door to rouse Marylou; our first look at her is of a languid young woman sprawled on a bed, completely naked. It certainly won't be the last time we see that much of the hungry Marylou.

Sal tells us Dean has spent a third of his life in the pool hall, a third in jail and a third in the public library. "He was conning me and I knew it. And he knew I knew it," Sal says. And yet he can't stay away from this conniving but charismatic man whose lust for life must have rivaled Henry VIII's. Eventually, Dean returns to Denver and Sal follows him there. It's the first of many trips across the country Sal makes with various combinations of characters -- though there's always a pretty girl along for the ride -- as the boys search out jazz, drugs, more girls, and, in the midst of all that, some meaning.

Salles gets the frenetic pace of Beat Generation antics right, but he only hints at Sal's ambivalence about this way of living. The novel "On the Road" was surprisingly suffused with religion. The wonder at the varieties of creation lead Dean and Sal to God, in a way, though they're not the type to talk much about it. As Dean says in the book, "We both understand that I couldn't have time to explain why I know and you know God exists." Dean wants to experience all of it; Sal comes to realize he might want only to experience the best of it. But Salles prefers to focus on the varieties of sex -- orgies were apparently pretty commonplace in 1940s Bohemian circles.

The English actor Sam Riley is just right as the American icon, while Sturridge is fabulous when not forced to mope in jealously of Dean's girls, and Hedlund brings the right combination of charm and almost innocent confusion. Kerouac's female characters weren't as well drawn out, but Stewart does the best with the meager material.

A standout is Viggo Mortensen, who plays Old Bull Lee, based on perhaps the most talented of the bunch, William S. Burroughs. "I find it unspeakably distasteful," Bull Lee says of Dean's carousing on other people's money. "Maybe that's because you don't see what's really holy about him," Sal responds. Salles doesn't really make us see, either. But he does give us a rather rollicking ride.