The Loneliness of the Later Intimacies : SECOND CHANCES<i> by Alice Adams (Alfred A. Knopf: $18.95; 257 pp.) </i>

In Alice Adams’ novels and short stories (the latter familiar to readers of The New Yorker), the lives of ostensibly ordinary people are captured and exposed to scrutiny like creatures embedded in polished amber. Her subjects tend to be upper-middle-class suburbanites, usually of liberal persuasions, experience some subtle, though pivotal, crunch of past and present. While her most recent book, an anthology of short stories (“Return Trips”) cast backward glances, this latest novel looks forward, all the more interestingly because its characters are nearing the end of their days.

Is there life beyond life, in the gray years, it asks? Yes, comes the answer, and it is no less charged with surprises, joy and tragedy than youth. It is, perhaps, only slightly gentled by the philosophy which results from experience.

In “Second Chances,” six long-time friends, most of them 60-ish and in one or another way attractive, have settled in the town of San Sebastian, south of San Francisco. They are, to all intents and purposes, an extended family. They are part of each other’s histories (a greater part, in some cases, than is openly acknowledged). They care for each other in a climate of mutual affection. They are generous toward one another: giving, forgiving and forbearing.

This tightly knit group is about to be enlarged by the advent of two younger people, comparative strangers. Sara, the goddaughter of widowed Celeste Timberlake, is coming to stay with her. Bill, Celeste’s elusive suitor, has been invited to meet her circle of friends.

These are Sam Venable, an artist; his writer wife, Dudley; Edward Crane and his lover, Freddy, and eccentric Polly Blake.

So begins a year in the lives of this group, a year in which past collides with present, destroying, rebuilding, sometimes offering redemption, as fate would have it.

To Sam and Dudley, it appears to hold a life beyond booze and brawling. To Edward, it promises a contented semi-retirement with the man he loves, though, to Freddy, it means his emergence from the closet as a gay rights activist. To Polly and to Celeste, it hints of romance.

Both Polly and Edward are keenly aware that life has already dealt them each a second chance in the form of recovery from cancer. Among these old people, the specters of illness and death are always present, unwelcome as persistent gate-crashers. With the advent of Sara and Bill comes a third uninvited guest, evil. These three, the author reminds us, are ever-present, even in the most congenial of circumstances.

Is Bill interested in Celeste for herself, for her money or perhaps for some more sinister purpose? And what has this to do with Sara, the former ‘60s radical? Tired of a fugitive life, grown weary and vulnerable under her veneer of toughness, Sara grudgingly accepts a haven in San Sebastian.

Nothing is quite what it seems here, however, and the lives of others, no matter how close, are, like the magnitude of an iceberg, largely concealed from view.

Contrary to first impressions, there are few, if any, ordinary people in Adams’ writing. Each is singular, though as familiar or approachable as an old schoolmate or someone we have just glimpsed in the post office or waiting at a stoplight to cross the street.

After her last novel (“Superior Women,” a success despite its shortcomings), it is a pleasure to find the author back in stride. With acute clarity of focus and economy of style, she constructs characters of sufficient individuality, depth and idiosyncrasy as to remain memorable, not to say missed, well after the last page has been turned.

Polly, the slightly comic philanthropist, hides under her haphazard costumes a heart full of courage, daring and passion. Celeste, a former actress, has grown adept at concealing her disappointments and conveniently reinventing her past. Edward, despite himself, is jealous and fearful for handsome Freddy. Dudley and Sam, still in love after 40 stormy years together are only now discovering each other’s fragility. As for Sara and Bill, the repercussions of their meeting, not to mention their politics, are incendiary.

As Adams traces the convolutions that bind this circle together, she delves into the complexity of their involvements and the secrets which, despite their long intimacy, lie buried among them.

In a larger sense, it is the nature of friendship under Adams’ delicate examination here. She re-creates, too, the haunting undertone of the loneliness present in all human intercourse, that separateness which, despite the presence of kindly acquaintances and lovers, can never be bridged nor breached.

The marvel of all this lies in Adams’ deceptively artless, straightforward narration. At its best, which it is in “Second Chances,” her writing flows with the seemingly ingenuous spontaneity of a Fred Astaire dance routine. It is also, one suspects, just about as easy to pull off.