IAN McEWAN is a British novelist and short story writer whose work has been being published at a steady pace, albeit in slender increments, since around 1972. His reputation in America is only now beginning to mature, but for some time he has been viewed by certain British critics -- A. Alvarez, for example -- as a high shining hope for British fiction in our time. Thus far, McEwan has written two collections of short stories, some plays for the BBC, and two novels. The first is called The Cement Garden. The second is the newly published The Comnfort of Strangers.

The Cement Garden is a slim, spooky book, involved with the sad perversities of an adolescent boy's first encounters with sex and death. It includes a corpse in the basement. The Comfort of Strangers also relies on perversity for its effects, although these have now grown a bit more "adult." It is also in ways a better book. It is better written. The elegance of McEwan's readabiltiy and technical skill -- invariably much admired -- have been brought to a higher luster and intricacy. The prose is richer, more allusive -- and McEwan's effects have grown more frightening. McEwan is noted for his jolting moments. True to form, certain pages in The Comfort of Strangers sent through this reader a couple of fairly impressive jolts.

Whether the novel thereby fulfills the ambitious claims made on McEwan's behalf is a different matter. I tend to think not. The Comfort of Strangers is a kind of highly refined lesson on the virtues and problems of a pure, distilled erotic fantasy as a source of novelistic energy. The book is a sexualized murder story, a kind of sado-masochistic (and much lesser) Death in Venice. Vacationing in Venice, a prettily named Colin and Mary, are taken up and courted by an older, "international" couple who call themselves Robert and Caroline. Unknown to the guileless Colin and Mary, Robert and Caroline, ruthless voyeurs, have been stalking the younger pair since their arrival. They have been transformed into a sacrificial male sex-and-death object.

McEwan proceeds through most of this sickly tale with subtlety and promise. He spins an atmosphere of quite real suspense all within an oppressive inexplicible ominousness. Like Mann in the original Death in Venice, he exploits effectively the atmospherics of the Emblematic Passerby: Boatmen with strange smiles, couples overheard quarreling in cafes; sexy roughhousing glimpsed in Lido Beach. Passim, he touches all kind of subtitles about eros, languor, the workings of desire, much of it in the context of a kind of feminist-tinted inflection of the sex war, here become a deadly business indeed.

The difficulty is that all this skill is directed toward a climax which, even though it is duly horrific, is sapped by a certain thinness and plain banality at its core. After an impressive wind-up, the sado-masochistic fantasy animating The Comfort of Strangers is elaborately revealed as . . . a sado-masochistic fantasy. And not much more. McEwan is anything but a vulgarian, but even he cannot finesse the lurid staginess the fantasy demands: The lascivious Robert and Caroline move in on their prey; the lethal razor glints in their hand; the handsome baffled male's tee-shirt is torn loose; he is murderously fondled, while poor hapless Mary gapes in horror, half-conscious but paralyzed by a secret potion slipped into her herb tea. The fantasized intensity grows first pale, then silly. The lovely hieratic Colin never dies here. It is the novel that dies. Colin merely vanishes in a puff of erotic fancy.

Yet The Comfort of Strangers has real interest as a novel. I confess I may not fully understand its strategies, a lapse I would of course rather attribute to McEwan's confusion than my own. In any event, McEwan is an exemplary novelist of our moment -- a role in the event both lucky and unlucky. In all his recent fiction, McEwan seems to be reaching toward some new imaginative accommodation to the sexual questions of innocence and selfhood, role and need that have defined, with such special intensity, his generation and mine. I honor him for his effort. At its best, it gives him what interest he has.

Yet I think the issues lose definition here. The sado-masochistic theme is false -- too simple, too thin. Moreover, throughout, McEwan alludes to feminist and anti-feminist rhetoric. The unfortunate Mary used to work in a feminist theatrical group, she and Colin (no feminist, but a Nice Guy), exchange some good boy-girl sparring over the Rhetoric. But elsewhere, the discussion is befogged: Caroline delivers herself hifalutin' intimacies over the joys of submission and pain: the murderous Robert (while displaying hints -- and more -- of homosexual attraction to Colin) delivers Italinate speeches about the good old days when men were men, and "proud of their sex."

This only clouds issues McEwan has treated better. In a collection of stories, In Between the Sheets (1978), McEwan published a short story which reads like a trial run of the obsessions that define The Comfort of Strangers. The story is called "Psychopolis." It is set in Los Angeles, and though it satirizes that city, there is something in the harsh argumentative contested atmosphere of American life that seems to do McEwan good. The story is hard with intellectual acuity and verve; it is a genuinely dazzling achievement, destined surely, for some place in the short story anthologies to come. "Psychopolis" is cruel in its vision, but in its 29 pages, it seems to me authentically to grasp the important issues that slip through McEwan's fingers in the novel he has given us here.