The novel’s metafictional elements are abundant but, until the end, quite subtle. One clue is that Tom Haley is a not-at-all disguised version of young Ian McEwan: their shared biographical details are legion, and McEwan’s real-life publisher, Tom Maschler, and his real-life literary compatriot, Martin Amis, both make appearances that are incidentally relevant to the plot machinery. Most notably, some of those short stories Haley writes are very similar, at times effectively identical, to stories McEwan published early in his career.

What is McEwan up to here? A weirdly refracted fictional autobiography? A meditation on the art and artifice of fiction? A commentary on the vampiric tendency of novelists to mine their friends’ lives for “material”? (Serena worries, with reason, that Haley is mentally recording their lovemaking sessions for his fiction.) John Barth, one of the postmodern writers that Serena explicitly renounces, has a short story, “Ever After,” in which the narrative concludes by referring to the piece of punctuation, a period, at its end; the story manages at once to inhabit its fictional universe and to stand outside it. McEwan here accomplishes something similar. The reader’s response (or at least this reader’s response) to the trick was a mixture of awe at the author’s cleverness and chagrin at having been so egregiously manipulated. Is McEwan merely playing devilish games at our expense?

But the novel’s emotional and intellectual satisfactions outweigh its frustrations. McEwan has pulled off something remarkable here: “Sweet Tooth” is a suspenseful plot-and-character-driven novel with an unexpected postmodern twist. It’s Jane Austen meets John Le Carré meets John Barth — not a combination that I imagine anyone has ever walked into a bookstore seeking. But it’s one whose delights turn out to be considerable.