By Lewis Shiner

Doubleday. 233 pp. $18.95

In the window of the local skate shop, amid the Body Glove and Jimmy's clothes, the Airwalk shoes, the Swatch watches and the Dr. Bonesavers Ramp Jammer Street Knee Pads, two T-shirts were recently on display.

One featured a barred circle superimposed over the ideogram of a businessman's suit.

The other conjoined a peace sign with the boast "Jobless."

Dave -- the fortyish, surnameless protagonist of Lewis Shiner's third novel, "Slam" -- might be pictured, by story's end, comfortably and happily wearing either of these shirts. But at the novel's start, when Dave's wardrobe is characterized by the description "None of his T-Shirts said anything," the reader is hard pressed to imagine that Dave will ever emerge from his slough of despondency and get out of his own way long enough to make anything of his life.

"Slam" traces the evolution of Dave's character and consciousness, his personality and his relationship with the intriguing residents of the town of Surfside, Tex., in such a sure-handed, low-key, convincing way that the reader has no trouble believing the invigorating transformations Dave undergoes in the eventful week covered by the narrative.

Emerging from a six-month stint in prison for tax evasion, Dave has found, with the help of his longtime lawyer friend, Fred, a job as caretaker for the estate of an eccentric elderly woman who has willed her property to her cats. Initially, I found this somewhat tired device a stumbling block to belief. But in the best Hitchcock manner, this old gimmick serves merely as a MacGuffin to give impetus to a truly original story. And this element, never overemphasized, gradually fades into the background, until finally it proves a convincingly essential piece of the book's climax.

Ensconced in the woman's beachside house, Dave anticipates a period of calm wherein he can get his bearings. Instead, events quickly spiral out of control. Several locals -- an over-the-hill sexpot, Mary Nixon; a UFO-believing preacher, Bryant C. Whitney; a treasure-seeking handicapped elderly couple named Barbara and Charles -- all have a claim on the estate, and thrust themselves egregiously into Dave's life. His parole officer, a Big-Nurse-type named Mrs. Cook, subjects him to merciless humiliation, all ostensibly to promote his "rehabilitation."

But these neatly quirky, sharply depicted oddballs have no basic effect on Dave's life and outlook. That enlightening force is provided by a girl named Mickey and a crew of young skateboarders squatting in an empty architectural folly known as Fonthill.

Dave meets the hard-bitten Mickey at her convenience-store job, is instantly smitten and soon becomes her lover. Pulled into her youthful milieu, where the music is loud and fast and nothing counts but the skater's moment of airborne ecstasy, when "all laws were suspended, no rules applied," Dave gradually comes to reassess his own life, to ask hard questions about what the individual owes to society, society to the individual.

Making love to Mickey one night in the sea, Dave experiences a moment of satori. "He was the ocean. He was miles deep and thousands of miles wide. Vast, eternal, rhythmic. Everything made sense. He saw where he had to go and what he had to do and who he had to become."

This moment of self-knowledge will stand Dave in good stead when the machinations of Terrell, an escaped fellow con who comes to live with him, bring even Dave's modicum of security crashing down around his ears.

Dave emerges from his moment of peril and testing battered, emotionally roughed up, but with a confidence and sense of mission he never enjoyed before. In the parlance of the skaters, he's taken a "slam," hit the concrete. But like Bobby, the skater who still performs after landing on his unhealed, recently broken arm, Dave proves his mettle by picking himself up and going on.

The evolution of Dave's character, Shiner subtly tells us, parallels an ongoing, incomplete social evolution, from a post-'60s despair, through the self-indulgence of the '70s and '80s, into a responsible anarchism, a kind of libertarianism with a heart. As the young skater Bobby says, "Concrete is the future. You don't cry about it, man, you skate on it."

Shiner employs a subtle, understated prose clear as the lacquer on a skater's new deck to tell his story. The mundane, absurdist details of contemporary life, the irrational, deracinated lifestyles so beloved by the minimalists, are faithfully evoked to explain Dave's dissatisfaction with his own life. But melded with this style is the melancholy humor and shaggy-dog diversions that can be found in any of Philip K. Dick's realistic novels, such as "Mary and the Giant" or "The Broken Bubble," along with the kind of sharp-witted street talk Elmore Leonard is noted for. Yet this stylistic blend, uniquely Shiner, quickly engages the reader's sympathies and propels the story along.

Outside the skate shop where those T's were displayed, the kids congregate. One of them -- a gamin-faced androgynous 10-year-old -- lifts his or her foot waist-high and stands on one leg. A friend cups the lifted sneaker. Then, without warning, the performer hurls herself off the ground, pivoting in midair. Sometimes she lands flatfooted, sometimes she slams. In either case, she doesn't wait more than a few seconds before trying it again.

Watching this single-minded exertion is a little like reading Lewis Shiner's "Slam." The reviewer writes frequently about contemporary fiction.