BOOK REVIEW : An Elusive, Unexpressive Story of Slaves From Different Worlds : CAMBRIDGE <i> By Caryl Phillips</i> ; Alfred A. Knopf; $19; 185 pages

Caryl Phillips renders slavery as a single nightmare shared between the dreamer and the dreamed, the enslaver and the enslaved. “Cambridge” is two stories that, in one sense, barely touch each other; in another sense, they are the same.

Each story has a protagonist and each has an island. The islands--Britain and a Caribbean island, which may well be Phillips’ birthplace of St. Kitts--are real enough; but they are cloudy, as if oppression and gross injustice had their own moral boiling point, beyond which reality vaporized into hallucinations.

“Cambridge,” elusive and sometimes self-indulgently so, is set in the early 19th Century. Emily Cartwright, a 30-year-old spinster, has been sent by her absentee-landowner father to visit his sugar plantation and give him a report on it. Upon her return to England, she is to marry a wealthy, middle-aged associate.

The father delivers this instruction with a hint of regret, but no opening for refusal. He needs the wealthy connection to maintain his extravagant lifestyle. He is fond of Emily, but she is his possession and exists to serve his convenience.

The same is true of Cambridge, a redoubtable, fiercely Christian plantation slave. Cambridge and Emily have only a peripheral encounter--though there is a fatal indirect link between them--but each lives the poisonously unreal life of bondage; openly, in one case, disguisedly in the other.

Emily tells her story in the prim tones of an early Victorian traveler. Welcomed to the plantation house by Stella, the loving and majestic slave housekeeper, she speaks of its comforts with a plangent sense of discomfort. She is appalled by the heavy meals, the noisy, barefoot servants. She employs a governessy archness on the subject of mosquitoes: “Once these gentry smell the blood of an English arrivant they are quick to strike.”

But we sense the pain of her uprooting and her estrangement. She bitterly laments the shipboard death of her lifelong servant and companion. Slavery offends her, though she is quick to excuse it by adopting the explanation that they are helpless creatures and need a master. She is more deeply offended by Arnold, the brutal overseer who digs mud from his boots at the dinner table and keeps a slave concubine.

But she has no authority, no authenticity, no identity of her own. It is her slave condition. And she will tell us, with scarcely a break in her genteel tones, of softening toward Arnold and being seduced. And, almost in passing--or in a numb trance--that she has seen Arnold beat Cambridge and, later, that Cambridge has killed him and been hanged for it. Later, as she disintegrates, the narrative shifts to the third person. She has lost her one possession: her voice.

Before this, though, we shift to the stentorian, Biblically-inflected tones of Cambridge, writing his story in the hours before his death. In a sense, it is the mirror image of Emily’s.

Taken from Africa as a youth and put on a slave ship, he has the fortune to find himself not on a plantation, but serving in the London household of a former slaver. His master is benevolent and sees to Cambridge’s education, treating him as the free man that, under the law applied to Britain but not to the Colonies, he has become. Upon his master’s death, Cambridge marries a white servant and tours England as a preacher for the anti-slavery movement.

England is as deceptive and hallucinatory to him as the Caribbean island is to Emily. Sent with funds to preach in Africa, he is robbed and imprisoned and ends up in the Caribbean sugar fields, a slave once more.

Phillips, author of “A State of Independence” and “Higher Ground,” is not at his strongest in this book. For one thing, the two narratives are so separate that we get a feeling of disjointedness and even of a sluggishness of effort. More seriously, although well voiced in terms of the two speakers and their histories, the narratives are deficient in spirit and expressiveness. What Phillips does succeed at, however, is suggesting the sickness of spirit and imagination that infects the slave world and those who run it.

Next: Elaine Kendall reviews “Summers With Juliet” by Bill Roorbach (Houghton-Mifflin).