Solitary Man : ALTERED STATES.<i> By Anita Brookner</i> .<i> Random House: 229 pp., $23</i>

Once again, in her 16th novel, the Booker Prize-winning author of “Hotel du Lac” has written a minutely observed study of a solitary individual. Her narrator, Alan Sherwood, is a solicitor, self-described as “stolid and prudent and slightly behind the times” yet “capable of passion.” He is very close to his mother, a “sensitive and civilized” woman who married an older man, the father of two of her friends, and was left widowed with her young son at an early age.

“Altered States” focuses on the turning point in Alan’s life, when his options close off just as his mother sensibly succumbs to the cultivated gentleman who has courted her for years. Alan’s constriction is largely due to an obsessive and unrequited relationship with his father’s granddaughter Sarah--that is, the daughter of one of his mother’s old friends--that leads him to make several big mistakes. The book details an essentially practical man’s loss of control over his life and the drastic measures he takes to regain that control.

Brookner’s old-fashioned, prematurely aged narrator, about 30 when his story begins and 55 as he reflects back over it, casts a fussy aura over his tale of obsession coupled with curious passivity. “Altered States” is enlivened by Brookner’s trenchant wit--”if peasants exist they are mostly indoors watching television,” she has Alan observe--but not enough to entirely relieve its somewhat claustrophobic focus.

The plot is in many ways a saga of frustration, for Alan’s attraction to evasive, elusive Sarah Miller is an exercise in futility. Both Alan and the reader know this from the start, just as he knows that Sarah is “vain, unreliable, and feckless” and “neither clever nor generous.” She is also monumentally rude.

But that doesn’t stop him from pursuing the young redhead. He notes that “at the beginning of an affair one does not count the cost. Already I knew that there would be an affair, and that it would not lead to possession. This did not deter me: I had confidence in the strength of my own desires.”

Sarah is so unrelievedly awful, however, that the reader can understand Alan’s frustration but not his attraction. This is a bit of a problem. After their first time in bed together, Alan describes their exciting “wordlessness,” but whatever excitement he manages to convey to the reader is negated by her nasty response when he asks her to dinner that night. “Don’t be a bore, Alan” she snarls. “Don’t cling.”

Somewhat to the reader’s exasperation, Alan persists, even when she fails to answer his calls or to be at home for his visits. Alan finds that Sarah is “a woman whose very presence was unsatisfactory, but whose absence was worse.”

Although Brookner’s story concerns an ingrown albeit convoluted family, there’s very little family feeling here other than between Alan and his mother. One of the few other warming relationships in the book is between Alan and his oldest friend and law partner, Brian, a hearty fellow refreshing in his lack of self-consciousness.

Sarah, however, is heartless not just to Alan but also to her mother, Sybil, and to her Uncle Humphrey and his new wife, Jenny, despite their strong attachment to her. Yet, with a precision characteristic of Brookner, Alan observes, “I had to admire the sheer consistency of her extremely inconsistent nature. She was unpredictable, yet she could also be relied upon to be unpredictable.”

Eventually, even Alan has enough of this. But in his “bafflement, estrangement, distress,” he falls ill, which leaves him wide open to Sarah’s rather pathetic friend Angela. Angela stalks him at the coffee bar where he breakfasts every morning and homes in on him like a hummingbird to sugar water.

Angela is after the social position that comes with marriage--a subject dear to Brookner’s heart. But she changes immediately upon marriage, regressing to “voluntary invalidism” even before she miscarries their daughter.

This profoundly immature and entirely unsympathetic woman--as horrific in her way as Sarah is in hers--has “no known disease but an apparently inexhaustible desire for guardianship.” Jenny comes to tend Angela, but she is as needy as Angela, and Alan finds this a further disruption of his peace and “a monstrous pantomime of filial and maternal affection.”

What we get, then, is the intense despair of entrapment, which Alan tries to bear nobly. Neither his home nor his life is his own anymore. We are actually relieved when Angela takes her life but, alas, Alan isn’t. His shock soon turns to guilt, which takes up permanent residence.

Like many of Brookner’s characters, Alan is a victim of his own compunctions as much as of circumstances or society. He renounces all possibility of a happy life in favor of a solitary one dedicated to work.

He grimly, dutifully looks after the widowed Jenny, who like Angela is always “obstinately waiting to be waited upon” after her small stroke. He visits weekly in her claustrophobic apartment, the halls of which make him feel “as if trapped in an anteroom to old age,” and spins Sheherazade-like tales about someday finding Sarah again.

His self-inflicted penance is stultifying, reminiscent of the bleak entrapment at the end of both Edith Wharton’s “Ethan Frome” and Wallace Stegner’s “Remembering Laughter.” Yearly visits to his mother at his country house and a “dreadfully quiet room” in a “monumentally dull” hotel in a town on the Swiss-Franco border offer little relief. (This place makes Brookner’s Hotel du Lac, where she exiled another solitary character to regroup after a scandal, seem scintillating by comparison.)

Are we to feel sorry for Brookner’s character? Aghast at what a life can come to? Admiring of rarely displayed moral fiber and discipline? Although keenly observed, Brookner’s “Altered States” is, in the end, a depressing portrait of a descent into “contented mediocrity.” Her writing is as supple as ever; it’s her subject that is tiresome.