Before Colin Harrison begins rolling out the 400-plus pages of mayhem and gore in his new novel "Afterburn," he offers up an enormously telling quotation from Jean-Paul Sartre that begins, "Torture is senseless violence . . . "

It's not the quotation itself that's revealing, but Harrison's decision to include it.

To begin with, it shows that he considers the gross brutality he depicts to be integral, even central, to his creation, not just some cheesy attempt to stir base emotion. Whether the story would stand without the torture scenes is questionable, but they surely are the book's most memorable passages.

One character, Rick Bocca, loses his arm to a bad guy with a circular saw who wants him to betray a woman he had betrayed once before.

His tormentors promise they'll drop him - and his arm - near a hospital if he'll talk, but it turns out to be a cruel hoax; the heavy cooler they give him to struggle with - one-handed - turns out to hold only a frozen turkey. It, too, has had one wing severed.

Another character, Charlie Ravich, has his decades-old scar from spinal surgery opened because the syndicate's sadist observed spinal anesthesia once and wants to give it a whirl. The motivation for this evil is the same: to get at the girl.

Such machinations by bad guys is boilerplate stuff; what makes "Afterburn" stand out are the long and specific descriptions of violence. Bocca's torture scene, which includes having a power drill ground into his ankle, his chest, then his mouth, lasts about a dozen pages.

Besides placing violence at the center by invoking Sartre, Harrison seems to be crowning his work as high art, not just as another mob-infested tale of sex and violence in the big city. Unfortunately, although the tale elicits a modest urgency to see what will come next, and offers some nice turns of phrase, what follows does not approach the lofty goal he set.

Substantial portions of the plot don't lead anywhere, and although there are some amusing and perceptive characterizations, they are of mere bit players; the main characters we have seen before. In addition to Bocca (the muscle-headed lug trying to make good on an old debt), and Ravich (the titan of industry with a personal void), there's the ruthless gangster, the cop on the pad, and a few others from central casting.

At the center is Christina Welles, a thief and schemer who nevertheless evokes a certain sympathy, in part because her brilliance is all she has. Her father was the last man not to let her down, and even he went and died on her. She fell for Bocca, a small- time hood, but when their scam went bust, she was arrested and he disappeared. The plot skips from one man to the next, each one trying to get something from her.

Most of the sex involves her, too. Although it has second billing to the violence, it too is exaggerated. What she and Rick used to do with, and to, each other is Olympian, as is what Rick does with a couple of prostitutes in the hours before the torture begins. Although it would be the last time it could ever be said, he had both hands full.

Ultimately, the Sartre quotation is not a symbol of high art, but of high pretentiousness. If it serves any purpose, "Afterburn" gives one author's view of how extreme sex and violence have to be these days to make pulp fiction stand out.