A SIGN OF THE EIGHTIES By Gail Parent Putnam. 319 pp. $17.95

Love child Astra Rainbow Blakely, 5 years old, has ridden her mother's hip across the United States from commune to commune. It is the early '70s, and Astra and Helen, her mother, are in a park in Seattle, where Helen is getting high with new friends. Unnoticed by her mother, Astra winds up in a shoving match with a bigger boy and before she knows what is happening she is pushing the boy off a cliff to his death. No one knows how he died; no one will believe Astra Rainbow when she tries to tell them. Unpunished, and therefore unforgiven, she lives the next 18 years knowing she must ultimately pay for her sin. She grows up to be a beautiful, blond, totally humorless creature who yearns to be a nun, whose primary characteristic is a Christlike innocence and whose destiny it is to redeem the flawed lives of three other people.

Malamud, right? Not exactly. This poignant and somewhat unbelievable tale of modern redemption is really only the machinery that moves the gears of Gail Parent's new urban comedy, "A Sign of the Eighties." It is an uneasy alliance between the portentous and the flip that doesn't quite work. It is as though one of Malamud's archetypal characters had a collision with the cast of a Neil Simon play and they all wound up in one vehicle, the eternal and the trendy ricketing along together to their destiny on the upper West Side.

The novel's real protagonist is Shelly Silver, a 35-year-old unmarried woman with her own successful catering business, an elegant apartment on the upper West Side and a desperation of heroic proportions. Shelly wants a man. The man she wants is Mickey Burke, and she's just right for him: He writes comedies for television and she is a sucker for a laugh. He needs nurturing and she comes with her own portable oven. He is the center of his universe, and he is the center of hers. But he can't love a woman who understands him and will give him unconditional love -- he keeps falling for distant blonds who don't get his jokes.

Astra Rainbow fills that bill perfectly and thereby, creakily, hangs the tale: Shelly yearns for Mickey; he lusts for Astra Rainbow (what's more distant than a woman who's waiting for her call to the convent?). Astra Rainbow sees in Mickey a virginal way to salvation. So Mickey is the hinge for all the action in the book, but unfortunately, he's the least believable of all the characters. We're told that he is complex and full of anger, but the rage is glued onto a character whose highest level of emotion is really more like annoyance. The altruism that Astra later brings out in him is equally questionable. What is real about Mickey is his self-centeredness. That is fully drawn, completely believable, infuriating -- and definitely a sign of the '80s. "Me First" is embroidered on this man's DNA, and that's a real problem for the book; it's hard to believe Shelly loves and wants him, or that he might ultimately make room in his life for her.

Shelly is a very real and very funny character. Touching, too: We see her beg Mickey to marry her ("I want to feel safe. I want kids. I'm tired of holding my stomach in."), hand him an ultimatum when he refuses and then literally crawl back to him, and we ache for her. The only thing stronger than this woman's passion is her feeling of inadequacy. Her sidekick, Greta, is the perfect foil, an enterprising desperate woman. Shelly meets her after one of her breakups with Mickey, when the two of them converge on a funeral in hot pursuit of the bereaved, Barry. Greta makes Shelly an offer: "From now on I'm going to run my love life like my business. Let's say Barry is the product. I'm willing to go for it, defects and all ... So, what do you want for him? Thirty-three-fifty is my top price, and you have to admit he's an inconsistent caller."

In fact, what works in this novel is the interaction between the women. There isn't a single false note in the scenes between Shelly and Greta, Shelly and Astra Rainbow, or Astra Rainbow and Mary, her friend whose idea of luxury is to make love lying down. But the flip sitcom humor that carries the book and the harrowing subplot of the guilt-ridden child killer never mesh. This is too light a book to bear the burden of the meaning Parent superimposes upon it. However, what's funny is very funny, and that includes a deadpan picture of the role of separate co-op apartments in the love affair of the '80s -- New York humor at its sharpest. To be funny is rare enough; to be funny and profound is given to mighty few, and when a writer tries for it and misses, only uneasy laughs are left.

The reviewer is the author of "Bed Rest" and of the recent novel "To the Tenth Generation."