The Women and the Warriors : THE GATE TO WOMEN’S COUNTRY<i> by Sheri S. Tepper (Foundation Books/ Doubleday: $18.95; 288 pp.) </i>

Science fiction novels are like Frankenstein’s laboratory, a great place for experiments. Sometimes what comes out is a monster, of course, but sometimes the rearrangement of facts produces beauty. And the process is always interesting. In Sheri S. Tepper’s lively, thought-provoking novel, “The Gate to Women’s Country,” the subject of the experiment is human gender.

Nearly three centuries after nuclear war, a number of small cities, surrounded by radioactive desolations, are thriving on the Northwest Coast. Inside the city walls live children, women, and some men called Servitors. Outside the walls, in garrisons, live most of the men. They are called Warriors, and do nothing but train for war and occasionally fight one with the Warriors of other cities. The women keep everything else going; they do the herding, farming, manufacture, trading, education, governance. At age 5, a boy goes to live in the garrison, and at 15, he must choose either to go for glory as a Warrior or return in shame through the Gate to Women’s Country into the city, to lead the inglorious and enigmatic life of a Servitor.

There are some mavericks outside this system, bandits and nomads, and late in the story, we meet the hill-folk of Holyland, a religious patriarchy founded on full-blown misogyny. St. Paul and the Ayatollah would love it. These inbred hillbillies don’t offer much threat to the Women’s Cities. The threat comes, rather, from their guardians and protectors in the warrior garrisons.

The thought-experiment sounds like it might be a feminist one, and in many ways this is a feminist novel--in the author’s unbothered acceptance of a society managed by women, in her evident disgust with traditional male self-indulgence and yearning for a strong, peaceable male temperament, in the complexity and open-endedness of the presentation. But it could please anti-feminists, too, by being “essentialist”--by apparently working on the assumption that there are unalterable masculine and feminine “natures,” that women are not just culturally but genetically disposed to be nurturing and domesticated and men to be aggressive and masterful. Freud and Schlafly would love it.

The plot starts from anatomy-as-destiny, but it is ingenious, packing a wallop of a surprise which I don’t want to give away, and so will describe only as an attempt to use genetics to change destiny, to redesign human gendering so that society won’t be forever crippled by male supremacism. If the genetic engineering is geared toward female supremacism, of course, it’s a dubious enterprise; where does tit for tat get us? Tepper isn’t naive about these questions. She handles her explosives with skill and offers no easy answers.

Indeed I find her book more interesting than the much-praised “Handmaid’s Tale” by Margaret Atwood, a cautionary novel that can be perceived as wallowing in what it cautions against, and which ends in the chic blank of noncommitment. Tepper isn’t anywhere near the artist Atwood is, but she knows how to write a well-made, on-moving story with strong characters, and she uses her anger honestly. She takes the mental risks that are the lifeblood of science fiction and all imaginative narrative.

The weak point of the novel may be sex, as distinct from gender. Homosexuality is cheerily dismissed as a “curable” result of “hormonal imbalance during pregnancy”--in other words, homosexuality is a disease caused by women! But the resulting exclusive heterosexuality doesn’t seem like all that much fun. The Warriors get sex with the Women only one month a year and are content to spend the other 11 months worshiping a giant phallus; the Women and the Servitors settle--apparently--for even less. The young protagonist becomes infatuated, and we hear that “parts of her went all wet-crotched at his words.” I want to know what parts--her ears?

That line, in its cringe-making ineptness, sticks out of Tepper’s competent prose and makes me suspect that this is a novelist who isn’t really at ease writing sex. Good for her! There’s so much easy sex in novels, it’s like being suffocated in marshmallow creme. Tepper’s awkwardness is more honorable than any amount of mere lubrication.

All through the book, as a kind of ground bass or recurring theme, run the rehearsals for a play called “Iphigenia in Ilium,” which the women perform annually. It takes nerve to rewrite Euripides’ “The Trojan Women” as part of a science fiction novel. The gamble pays off. What Tepper is writing about is war and peace, the cause and the cost of each. The strength and the passionate sadness of the story’s end aren’t just borrowings from Greek tragedy; they are tragic in the real meaning of the word.