By Elizabeth Moon

Ballantine. 340 pp. $23.95

"Sometimes I wonder how normal normal people are," muses Lou Arrendale, the protagonist of Elizabeth Moon's splendid and graceful new novel, The Speed of Dark. Lou is not what most people would call "normal." He is autistic, and the heart of this ambitious, beautifully crafted book is his conflict over whether to engage in an experimental medical procedure that will make him normal -- i.e., like "most people," people like Lou's psychiatrist.

"When she . . . looks at me," Lou says, "her face has that look. I don't know what most people would call it, but I call it the I AM REAL look. It means she is real and she has answers and I am someone less, not completely real."

In Moon's very-near-future America, gene therapy has made it possible to cure neurological defects that cause the vast spectrum of autistic syndromes during infancy. Lou was born a few years too late for such a procedure, though early-intervention education and treatments have made it possible for him to live comfortably in mainstream society. Now in his late thirties, he has a job, an apartment, a car, friends who are, like himself, autistic, and friends who are not.

He works at a multinational pharmaceutical company, where he is one of a small number of autistic employees. His job is to scan a computer monitor, identifying patterns in the lines of symbols and numbers scrolling past so that the results can be used to develop new synthesized drugs.

Then Gene Crenshaw arrives as new division manager. Crenshaw's first order of business is to get rid of the autistic workers, whose specialized working conditions -- individual offices, their own enhanced gymnasium -- strike him as wasteful. He views their work with equal parts incomprehension and scorn. He threatens the autistic workers with dismissal unless they volunteer for a human-trials research protocol, a combination of drugs and nanotechnology that has been used successfully in animal trials but never on human subjects.

At first, Lou and his co-workers are angry, frightened and intimidated; fortunately, they have a sympathetic boss who immediately starts scrambling to obtain legal and medical assistance for them. But, of course, the volunteer trial is not just a threat: It's also a promise. If it's successful, Lou and his friends will finally have the opportunity for a normal life -- but what exactly would that mean?

Inevitably, The Speed of Dark has been compared to Daniel Keyes' classic and tragic Flowers for Algernon, in which a mentally disabled young man is medically enhanced to become a genius. The Speed of Dark may be an even greater book. True, Moon's plot deployment is rather clunky -- Crenshaw is such a model of rabid political incorrectness that it's hard to imagine him ever climbing the corporate ladder. But her novel isn't exactly intended to be a thriller; it is, rather, a subtle, eerily nuanced character portrait of a man who is both unforgettable and unlike anyone else in fiction.

Lou's obsessive attention to pattern details is what makes him brilliant at his work. His sensorium is so exquisitely attuned to them that, upon entering a room, he immediately notices the number of squares in a rug, their colors, the manner in which they are replicated. He sees, and hears, intricate patterns everywhere: in music, real and imagined; in cars lined up in a parking lot; in the fencing maneuvers his friends practice; in the stars overhead; and in the seemingly random movement of the pinwheel mobiles hanging in his office.

Yet he has difficulty following group conversations and identifying the emotions behind a sarcastic remark, or understanding what might impel a "normal" friend to harm him. As Lou begins to research the possible side effects of Crenshaw's experiment, as well as its moral and ethical dimensions, he also begins to weigh what he stands to lose -- the intense friendships he has made with a group of amateur fencers; his relationship with Marjory, a young woman he is in love with; his autistic friends, who may very well become unknowable to him after medical intervention; most of all, the self-knowledge and confidence that he posseses.

"I glance around my apartment and think of my own reactions, my need for regularity, my fascination with repeating phenomena, with series and patterns," he reflects. "Everyone needs some regularity; everyone enjoys series and patterns to some degree. I have known that for years, but now I understand it better. We autistics are on one end of an arc of human behavior and preference, but we are connected."

In popular media, those with mental or behavioral disabilities are often portrayed as liminal beings, magical creatures whose disorderly lives redeem them or (even better) redeem us "real people." Think of the saintly savants in the films "Rain Man" and "Being There," the winsome lunatics of Phillipe de Broca's "King of Hearts," the martyred Randall McMurphy in Ken Kesey's One Flew Over the Cuckoo's Nest. Too often, such characters are cardboard pasteups who represent an author's or filmmaker's agenda, not real people tethered to jobs and families and daily routines.

Moon, the parent of an autistic teenager, very quietly explodes all those stereotypes: The disorder can be heart-wrenching, frightening, isolating, challenging for people born with the syndrome and those close to them. Lou is an extremely high-functioning autistic, but he makes his way very carefully through a confusing world that, despite his career and that nice gym, makes few concessions to him or his co-workers. That it is "important not to scare people" is something he has learned through experience and observation; but even under close scrutiny, ordinary human interaction baffles him. Unsure whether Marjory likes him, Lou notes that normal people "know when someone likes someone and how much. They do not have to wonder. It is like their other mind reading, knowing when someone is joking and when someone is serious, knowing when a word is used correctly and when it is used in a joking way."

The end of The Speed of Dark is not unexpected, but it is marvelous all the same, and exceptionally moving in its balance of loss and wonder. "The edge is what I have," Theodore Roethke wrote in his most famous poem, "In a Dark Time"; what Lou Arrendale gradually realizes, what he ultimately gambles on, is that the edge is not all he has. It is a measure of Elizabeth Moon's genius that she enables a reader to thoroughly experience the world through Lou's tangled but exhilarating neurology, and wonder what we "normal" people are missing when we don't acknowledge our connection to those who seem so different from us. A lot of novels promise to change the way a reader sees the world; The Speed of Dark actually does. *

Elizabeth Hand is the author of the forthcoming "Bibliomancy: Four Novellas" and "Mortal Love," a novel.