By Lynne Sharon Schwartz

Counterpoint. 297 pp. $24

This worthy novel may best be read as a passionate, sensitive love letter to the wounded city of New York. It's set during the months before, during and after what we have to come to call 9/11. Renata, a 34-year-old single woman, has been carrying on an affair with Jack, a divorced, middle-aged, independently wealthy man who is a self-appointed freelance philanthropist. He helps individuals, on a case-by-case basis, as he sees fit. Although they both live in Brooklyn, Jack knows the Manhattan bureaucracies inside out. His cosmic calling, as he sees it, is to cut through red tape.

Renata's job is even more amorphous and singular: She works for the New York Public Library, analyzing all manner of indecipherable manuscripts and books that get sent to that venerable institution. Her mind is unique and wired strangely enough that after a few months, weeks or even days, she is able to make sense of foreign languages. Renata loves language; its misuse grates terribly on her. She lives by what Socrates wrote long ago: "False language, evil in itself, infects the soul with evil."

A few months before al Qaeda's destruction of the twin towers, Renata and Jack would seem to be living the most ordinary of lives. He has that ex-wife he's forgotten to tell her about, and she's gone through some things best left undiscussed, which the reader finds out about in selected flashbacks. But they go out to good neighborhood restaurants, fool around with silly word games and have plenty of athletic sex. They seem all right. But Renata's not all right.

This doesn't give away the plot, but it does leak a little of the backstory: Renata had a twin sister, Claudia. For their first 12 years or so, they were as close as twins "should" be. Then Claudia turned on Renata, stopped speaking their "secret" language and committed a teenage betrayal or two that never lost their sting. Claudia turned into a "bad" girl, got pregnant by someone unsuitable by any measure, had a baby, and then drowned in the Hudson River.

All this was followed rapidly by the possible suicide of their father and the breakdown of their mother, who chose amnesia over despair and ended up residing very comfortably in a sanatorium 17 miles up the river from Manhattan. Claudia's baby was cared for by people who soon got sick of the project; the baby turned up three years later, becoming Renata's sole responsibility when she was still a bereft teenager living alone. Then another unspeakable thing happened: After a few more years, the baby -- Gianna, now a girl of about 6 -- was kidnapped, abducted or simply disappeared into the streets of New York.

All this misery raises the question of the willing suspension of disbelief. The soul of the reader is willing to believe, but the brain rebels a bit. The more the unspeakable events pile on, the harder they are to believe.

After the towers fall, of course, the whole world becomes both unspeakable and unbelievable -- except as seen through the blase, amnesiac eyes of Renata's mother. Renata, whose mind has always been a little unstable, begins living in something like a fugue state. Just after the attacks, she finds a $20 bill that might be the very one her sister stole from her so many years ago. President Bush's wartime rhetoric afflicts her with a terrible rage, evoking for her the type of false speech that Socrates railed against so long ago. And after it falls to her to care for the baby of Jack's dead secretary for a few days, she finds it agony to yield up the infant to its real family.

Then, on one of the posters of the lost that plaster the walls and fences of the city, there's a picture of a missing girl of 16 or 17. Her parents are desperate and want her back. But in a city wracked with confusion and grief, Renata has already found that (conveniently mute) girl; in the same way that she thinks that the $20 bill she found could easily be the one her sister stole from her, Renata is convinced that the girl is Gianna, washed back up from the stormy seas of New York. When Jack and another well-meaning friend suggest that Renata might want to give the girl back to her family, she fiercely resists. She's been driven somewhat crazy by events, and her anguish mirrors that of an entire city left bereft, somehow orphaned, in deepest mourning.

"The Writing on the Wall" might best be read by New Yorkers; it's the kind of book that, like certain fine and very delicate wines, might not "travel" well and tastes best drunk in its own locale. But the author has done an admirable job in chronicling a trauma, monumental in its reach, whose echoes still resound.