By Michael Gruber

Morrow. 419 pp. $24.95 Michael Gruber's first novel, "Tropic of Night," is an astonishing piece of fiction, one that expands the boundaries of the thriller genre. I am not alone in my reaction -- it is a main selection of the Book-of-the-Month Club -- and you will hear more about the fierce intelligence of Gruber's writing, the complexity of his heroine, Jane Clare Doe, and the fearsome African sorcery that lies at the heart of the novel. Sorcery, magic, witchcraft -- by whatever name, no matter what you think about it now, you will take it more seriously after you've experienced this mind-bending novel.

Start with the heroine's name, Jane Doe. Why did Gruber call her that? Sheer perversity, I thought at first, but I came to suspect something more. As heartrendingly peculiar as Jane is, she is also, with all her fears and strengths and passions, a kind of Everywoman, so perhaps the generic name is fitting. When we first meet her, she is living in Miami under an assumed name, working at a menial job, hiding from her husband. She is, we learn, an heiress, raised in luxury on Long Island. While at Barnard, she fell in love with a celebrated French anthropologist and proceeded to live with him for seven years. They went to Siberia to study the Chenka, who are known for their magical powers. ("I once saw Puniekka turn into an owl. I once saw Ullionk, one of Puniekka's students, appear in two places at once. An old woman, seen in a yurt, looking up from her pot, had a dog's head.") The intensity of the Chenka experience broke the relationship and almost cost Jane her life.

Recovering, she met Witt Moore, a handsome young black poet and playwright. There was anger in Witt -- his first play was a bitter satire of white America -- but they fell in love and married. When Jane was invited to join a team of anthropologists in West Africa, Witt accompanied her. After they lived with the Olo tribe and studied its extremely potent sorcery, Witt underwent a transformation. He declared that the world needed a "black Hitler." When they returned to the United States, he used his new powers to kill someone. Jane, terrified, faked her suicide and fled.

Three years later, in Miami, soon after Jane has adopted an abused 4-year-old girl, she hears of the ritual murder of a pregnant woman. She knows at once that it is her husband, practicing the forbidden Olo okunikuaor fourfold sacrifice. Once he has killed four pregnant women and their babies, and eaten parts of them, he will achieve superhuman powers, which Jane fears he will direct against white America. "The Olo call it jiladoul, the sorcerers' war. You wonder why there are only twelve hundred Olo left. That's why."

The police investigation is headed by an unlikely but memorable duo, detectives Jimmy Paz and Cletis Barlow. Paz is Afro-Cuban, genial and shrewd, and very much the ladies' man. ("He had always had several relationships going on, never more than four, never less than two.") Barlow is a scripture-quoting fundamentalist. When witchcraft becomes an issue, Paz scoffs, but Barlow accepts it easily: "The smartest thing Satan ever done was making folks believe he ain't real."

The novel alternates between the progress of the murder investigation and flashbacks to Jane's earlier life. Actually, more space is given over to Jane and sorcery than to the investigation. The book offers a running debate between magic and science, between those powers we understand and those we do not. The author plunges deeply into the world of magic, the better to make us accept the powers Witt unleashes near the end of the novel.

As the killings continue, Paz and Jane join forces against her husband. Jane still loves Witt and insists that he is not responsible for his actions, that he has literally been bewitched. She tells Paz: "You know what real love is, Detective? It's not what you think. It's not loving the virtues of the beloved. Anyone can love you for your virtues, that's no trick. I mean, that's what virtues are -- lovable qualities. It's the unlovely stuff that makes love. We all have a little nasty wounded place in us, and if you can get someone to find that and love it, then you really have something."

In the novel's powerful climax, the detective watches helplessly as Witt's dark magic confronts Jane's goodness: "He heard screams. Geometries that the human brain was not designed to record occupied the room. Paz shut his eyes."

No summary can do justice to the richness and fascination of this novel. The author wields his own sorcery as he lures us into the hallucinatory world of his imagination. Gruber's bio says he worked on science policy in the Carter White House and that he has "held many jobs, virtually all of which have involved writing, usually anonymously." He won't be anonymous any longer.