A Daddy Fixation : THE LOST FATHER, <i> By Mona Simpson (Alfred A. Knopf: $22; 472 pp.)</i>

Chase after the white whale and you can end up with tuna fish. The young narrator and protagonist in Mona Simpson’s second novel bleeds her life into a search for her runaway father; until she finds him, and he’s nothing special.

If life is a journey rather than a destination, a single-minded purpose becomes an evasion. That is the theme. The child in Simpson’s first book, “Anywhere but Here,” who is taken by her scatty mother to Hollywood to become a star, is grown up now, and a medical student in New York. But she has never gotten over that first flight imposed on her. In “The Lost Father”--”Anywhere but Here” would fit even better--she takes up a flight of her own.

It is a flight that for much of the book is slow, fitful and erratic. It begins with her name. Mayan Atassi is what she calls herself, but for much of her girlhood she was Mayan or Ann Stevenson. Stevenson was her stepfather. Her father--her mother’s first husband--was John Atassi, a mercurial Egyptian who came to the United States to study, pursued an unstable academic career and, when Mayan was a child, took her out for a hamburger one day, brought her home, left, and never got in touch again.

“All you have to do to become somebody’s God is disappear,” Mayan declares partway through her account. She tells us in retrospect, after her search is over, and after the God is found to be a self-centered, middle-aged man who manages a restaurant in Modesto, is delighted to see her, and hasn’t the slightest notion, other than a mild guilt, that his silent absence misshaped her life and bent it into an obsessive quest.

Mayan centers her narrative on the year or so that follows her arrival in New York from Racine, Wis. She had done brilliantly at college and won a place at Columbia University Medical School. She is, in everyone’s opinion, a golden girl; yet now, on her own, she comes apart bit by bit. Nothing seems real to her: neither her studies, her tiny apartment, her friends, nor even a lover who leaves her, and to whom she writes dozens of letters that she does not mail.

Perhaps it is his abandonment that connects her to the burden she has carried and tried to ignore since childhood. Beneath her achievements, her Midwestern thrift, reliability and diligence, her father’s flight has made her feel worthless or, as she puts it, “unwatched.”

From New York, she makes desultory efforts to find him. She calls directory assistance in various random cities. She pays a little money--she has a small inheritance from her grandmother but feels it’s wrong to spend it--on a detective, and gets a little useless work from him. She pays a good deal more to a higher-class detective, who puts on a show of activity and swindles her. She telephones the FBI, only to be told by the sympathetic operator that she has looked fruitlessly for her own father. Try the Salvation Army, she suggests, or therapy.

She lays down the search and picks it up again. “It is what I do,” she reflects. It drains her life; she begins to miss classes; her friends urge her to set limits on herself. A box of papers leads her on a fruitless trip to a small western college where her father once taught, and which he left under a cloud. She breaks down once or twice; she flies to Egypt, where a taxi driver makes love to her--exceptionally, the episode is banal--and where she finds her father’s family. They are hospitable but don’t know where he is. Finally, an old friend makes a suggestion that turns up John Atassi with comically anticlimactic ease.

The disability left by parental abandonment is a familiar theme. What Simpson does is to work out in enormous, sensitive and highly imaginative detail the pattern this abandonment describes in one individual.

Mayan, of course, is a highly special individual. She has her mother’s theatricality, less toughness, more scruples. Her language can be high-flown and self-dramatizing; her sentences move, at times, like ballet dancers: en pointe. “I wanted love, but a high, far kind that made my breath as if it wouldn’t last,” she tells us. After she finds her father and realizes he is not what she imagined, she says rather confusingly: “Then the world was stiller, less light. Spirit was not everywhere but a common, transient thing.”

Fortunately, this balletic toeing is only a variation. Mayan has a homely shrewdness; she can make a wonderfully acrid portrait of the swindling detective. There is a splendid and wintry indirectness in the efforts of two ancient retired professors at the western college to recall their disreputable colleague. And at the end, the mismatched expectations and transactions between Mayan and her father--there are love, anger and the beginning of awareness on her part; love and obliviousness on his--is rich human comedy in its most serious sense.

Despite such richness, “The Lost Father” has two major defects, and both have to do with size and proportion. One is that Mayan, precisely because her wounded abandonment and search turn her so inward, is only occasionally able to sense the reality of what is around her. It is her disability that her friends, her lovers, her studies, the New York she moves in, are so shadowy. But in a book of such length, this shadowy lethargy overwhelms. As for the search, when it moves, it comes wonderfully alive; but for long periods it barely creeps.

A second defect is a pitfall of narrative. Mayan tells about herself and her feelings with limitless insight and in limitless detail. At short-story or even short-novel length, this would be fine, because she does it very well. For long stretches, though, insight turns to self-involvement. Mayan is alive, believable and real; and as with any live, real and engaging person who talks endlessly about herself and doesn’t look up or out, you wish she would.