Kazuo Ishiguro writes a prose of provoking equilibrium—sea-level flat, with unseen fathoms below. He avoids ornament or surplus, and seems to welcome cliché, platitude, episodes as bland as milk, an atmosphere of oddly vacated calm whose mild persistence comes to seem teasingly or menacingly unreal. His previous novel, “Never Let Me Go” (2005), contained passages that appeared to have been entered in a competition called The Ten Most Boring Fictional Scenes. It began with dizzying dullness: “My name is Kathy H. I’m thirty-one years old, and I’ve been a carer now for eleven years.” The stakes of the characters’ interactions with one another seemed fantastically small; a friend and I had a running joke in which we imagined Ishiguro murmuring with satisfaction to himself, after a morning of hard work, “Say what you want, but I own the scene where Kathy loses her pencil.”

Of course, the stakes are eventually revealed to be fantastically large, and “Never Let Me Go” achieves great and moving speculative power, not because of what it has to say about the dilemma of cloning but because of what it has to say about ordinary life’s unwelcome resemblance to the dilemma of cloning. We gradually learn that the fictional children we encounter, who attend an English boarding school called Hailsham, are clones, created by the state in order to be killed: their function is to provide healthy organs for normal British citizens. Once they have completed their donations, they will die. The resignation of these children, who become aware of their fabricated function, is horrifying; most of the time, they seem sapped of rebellion. Ishiguro’s pithless, neutered prose is mimetically effective. It enacts a meek acceptance that finally may be our own, too. The children of Hailsham endure short, determined, and thus “pointless” lives; but are our lives—though generally longer—less pointless or less determined? The lives of the cloned children, who fall in love and read novels and bicker at school just as ordinary kids do, seem like parodies of real freedom, of real existence, because we know what will happen to them not long after they leave school. But perhaps our own lives are mere parodies of real freedom, of real existence? Life is a death sentence, whether you die at twenty or at eighty. Ishiguro’s novel can be seen as an inspired secular expansion of Pascal’s tragic religious vision: “Imagine a number of men in chains, all condemned to death, some of whom are executed daily in sight of the rest; then those who are left see their own fate in that of their fellows, and regarding each other with sorrow and without hope, wait till their turn comes: this is a picture of man’s condition.”

Ishiguro’s level banality has always been a rhetoric in search of a form. He doesn’t need the pressure of realism (though his best work is powerful surely because it exerts its own pressure on the real), and indeed his novels are daring in the way that they seem almost to invent their own gauges of verisimilitude. But he does need the pressure of form, a narrative shape that forces his bland fictional representations to muster their significance. It is typically the significance of absence, of what has been concealed or repressed. His complacent or muted unreliable narrators, like the painter Ono, in “An Artist of the Floating World,” or the butler Stevens, in “The Remains of the Day,” tell stories that mildly and self-servingly repress secrets, shameful compromises, and the wounds of the past. (Both of these narrators have reason to conceal or minimize their involvement with Fascist politics just before the Second World War.) Under this kind of pressure, blandness emerges as a traumatized truce, a colorless pact that holds the personal and historical present together at the cost of a sinful amnesia.

Unfortunately, Ishiguro’s new novel, “The Buried Giant” (Knopf), does not generate the kind of pressure that might wring shadows from the bemusing transparency of its narration. Thematically, it has obvious connections with the author’s earlier analyses of historical repression, and with the blasted theology of “Never Let Me Go.” It also has some consonance with the Kafkaesque dreamscape of “The Unconsoled” (a novel that has had able defenders since its publication, in 1995, but that has visited its own kind of amnesiac curse on me, since I can remember almost nothing distinct in its more than five hundred pages). But in his new novel Ishiguro runs the great risk of making literal and general what is implicit and personal in his best fiction. He has written not a novel about historical amnesia but an allegory of historical amnesia, set in a sixth- or seventh-century Britain, amok with dragons, ogres, and Arthurian knights. The problem is not fantasy but allegory, which exists to literalize and simplify. The giant is not buried deeply enough.

“The Buried Giant” is set after the end of a war between Saxons and Britons; they now live alongside each other, but warily. A widespread historical amnesia grips the populace, erasing both recent and distant memory. Axl and Beatrice, two elderly married Britons, call this forgetting “the mist.” Even memories only a month or two old fade away. Axl and Beatrice once had a son, who disappeared, but neither can quite remember him, or why he left them. They embark on a journey to visit him, a quest that occupies the rest of the novel. (Despite all this mental erasure, they seem to know that “our son awaits us in his village.”) In the course of the journey, they encounter two knights: Wistan, a young Saxon warrior, and Sir Gawain, an elderly and slightly buffoonish nephew of King Arthur, whose reputation, like Don Quixote’s, comically precedes him. There are adventures and battles with ogres, pixies, dragons, and menacing soldiers. There are some sinister monks. Along the way, Beatrice and Axl discover that “the mist” is actually the breath of a tyrannical she-dragon named Querig, and that the only way to restore the country’s stolen memory will be to kill Querig. The novel ends with the vanquishing of Querig and the inauguration of a new historical dispensation, in which people will have to reckon with what they have forgotten. The restoration of memory is a bitter pleasure, it seems: Beatrice and Axl recover their intimate past, but historically the mist has enabled a period of peace, wherein Saxons and Britons had productively forgotten their former enmities and grievances. “Who knows what old hatreds will loosen across the land now?” Axl asks, fearfully. Wistan, who appears to have supped full of anti-British grievance, agrees: “The giant, once well buried, now stirs.” He predicts savage warfare. But Beatrice and Axl, who are old, will likely not live to see this bloody future.

Tastes differ, and Ishiguro is welcome to his Arthurian chain metal. (You can’t help admiring a writer who so courageously pleases himself, who writes so eccentrically against the norms.) But a generalized Arthurian setting, perilous for most writers, is a larger liability for a writer whose mimesis tends not toward the specific but toward discursive monologue and dreamlike suspensions. A master of detail such as Marguerite Yourcenar could perhaps pull off such a project. You can imagine Willa Cather attempting, and possibly succeeding at, a fictional reconstruction of Native American life centuries before the arrival of Europeans. William Golding wrote a great book about the lives of Neanderthals (“The Inheritors”), and an even finer book, set in the fourteenth century, about the building of a great church spire, not unlike Salisbury Cathedral’s (“The Spire”). Chekhov wrote a moving story about an unpleasant coffin-maker, who has contrived, perhaps because of his buried grief, to repress the memory of his dead child, and who denies the child’s very existence even as his wife is trying to remind him of it (“Rothschild’s Fiddle”). But these novels and stories are rammed with texture and telling particulars; they are dynamic, sensuous, and concrete in a way that Ishiguro’s story rarely is. “The Buried Giant” has far too much dialogue like this, more Monty Python than William Golding: “Your news overwhelms us, Sir Gawain. . . . But first tell us of this beast you speak of. What is its nature and does it threaten us even as we stand here?”

Just at the technical level, can one write a successful novel about people who can’t recall anything? Ishiguro is always breaking his own rules, and fudging limited but conveniently lucid recollections: “After a while Axl could no longer remember how talk of this journey had started, or what it had ever meant to them. But then this morning, sitting outside in the cold hour before dawn, this memory seemed partially at least to clear, and many things had come back to him: the red-haired woman; Marta; the stranger in dark rags. . . . And he had remembered, quite vividly, what had happened only a few Sundays ago, when they had taken Beatrice’s candle from her.” Well, which is it, a mist or an intermittent rain?