To read Ian McEwan is to hold one’s breath as his intoxicating prose rushes inexorably toward some (probably unwanted) unknown.

This was so in his last novel – the beautiful and moving “Atonement” – and it is so in his latest offering, the marvelously rendered “Sweet Tooth.” Only this time one smiles, right from the novel’s opening lines:

“My name is Serena Frome (rhymes with plume) and almost forty years ago I was sent on a secret mission for the British security service. I didn’t return safely …”

Here again is deep deception, human guilt, human shame – and almost no one is the person he or she first seems. But here too are books as a prime focus. In fact, this is a book about books – and about the loving and reading and writing of books, as well as readers’ often-diverse responses to books.

Serena, for starters, is enamored of books even though, as “Sweet Tooth” begins, she is finishing a degree in “maths” from England’s time-honored Cambridge University:

“My needs were simple. I didn’t bother much with themes or felicitous phrases and skipped fine descriptions of weather, landscapes and interiors. I wanted characters I could believe in, and I wanted to be made curious about what was to happen to them … Nor was I impressed by reputations. I read anything I saw lying around. Pulp fiction, great literature and everything in between – I gave them all the same rough treatment.”

It is through a Cambridge boyfriend that Serena meets Tony Canning, a charismatic and celebrated history professor more than twice her age. His seduction of Serena is far more than that: He sees her as a prime candidate for undercover work with MI5, the British intelligence agency charged with national security, of which Canning is secretly a part.

Thus McEwan, a master plot-maker, sets “Sweet Tooth” in motion – against a backdrop of the Cold War in 1972. It is all heady stuff, inviting discussion of Serena’s youth, beauty and smarts combined with a certain naïveté, as well as the myriad ways men and women use and deceive one another, and the levels of guilt this does or doesn’t bring.

“Sweet Tooth” can also be read simply, as a riveting piece of espionage. Reader’s choice – and Ewan’s gift, either or both ways. What shines, as always, is McEwan’s prose, so seamless that he can describe an entire bar fight in a single paragraph, and leave the reader exhausted.

The working premise is that Serena, under the guise of an assistant desk officer at the Department of Health and Social Security, is to offer a “suitable” young writer (one who has already shown a propensity for the UK’s anti-Communist point of view) a cultural stipend from a respected foundation. An MI5 power-that-be explains Serena’s mission:

“You know as well as I do, it’s not straightforward to deduce an author’s views from his novels. That’s why we’ve been looking for a novelist who also writes journalism. We’re looking out for the sort who might spare a moment for his hard-pressed fellows in the Eastern bloc, travels out there perhaps to lend support or sends books, signs petitions for persecuted writers, engages his mendacious Marxist colleagues here, isn’t afraid to talk publicly about writers in prison in Castro’s Cuba. Generally swims against the orthodox flow …”

Key to this ploy – to influence the thinking of the masses – is that the writer know nothing of the real source of funding. The idea is not new. Melvin Lasky, an American journalist, took money for years from the U.S. Central Intelligence Agency, for the German and British anti-Communist journals he edited.

MI5’s operation, “Sweet Tooth,” includes other writers but Serena is to sign up its first novelist, a young man already in mind, Thomas (T.H.) Haley, who is studying for a doctorate at the University of Sussex. Serena is sent away with Haley’s file and the words, “Assuming you’re happy, we’d like you to get on the train to Brighton and take a look at him. If you give the thumbs up, we’ll take him on.”

At this point, Serena slips into a world of Haley’s stories – strange, compelling pieces that make her happy. Of course, the inevitable will happen: The two will fall in love.

But always, always there will be the deception that is Sweet Tooth. She is Haley’s lover and his traitor too.

“Tell him now. Tell him what you do,” she chides herself, other times thinking, “the truth was too weighty – it would destroy us.”

Prevarication, to a profound degree, informs much of Serena’s life by this time.

She must lie about her work – as she has been lied to, by Tony Canning, by co-workers, by circumstances she believes she didn’t choose.

“Tony had chosen my profession for me, lent me his words, ceps, opinions, worldliness,” she muses of her summerlong affair with Canning, one during which, unbeknownst to Serena, he groomed her for MI5. But he also enchanted her, and taught her about ceps (porcini), mushrooms much prized in Italy and France.

Canning betrays Serena early on in the book. Later, there are rumors he also betrayed MI5. Max, an MI5 colleague, tells Serena, “In this work the line between what people imagine and what’s really the case can get very blurry.”

What isn’t at all “blurry” here are the wonderful musings about and discussions of books, their creation, their words, their meaning. Serena and Tom speak endlessly of them, argue endlessly about them – and one gathers that many of their thoughts are those held or being weighed by McEwan.

Sweet Tooth, as a mission, will fail of course – and Haley will compare this to the successful World War II military deception known as Operation Mincemeat: “Mincemeat succeeded because invention, the imagination, drove the intelligence. By miserable comparison, Sweet Tooth, that precursor of decay, reversed the process and failed because intelligence tried to interfere with invention.”

McEwan’s use of a female protagonist – after his stunning portrayal of Briony in “Atonement” – is pivotal here. When, this spring, The New Yorker ran an excerpt of the early portion of the book, Serena seemed too green and too malleable to be of interest to Tony Canning, much less the MI5 – proving only that “Sweet Tooth” must be read in toto or readers, too, are going to be deceived.

As Serena puts it herself:

“I couldn’t have known in the beginning where we were headed, and as soon as I did know, it became too precious to threaten … All I could think of was never telling him. Could I live with myself? Well, I already was.”

“Sweet Tooth,” in sum, is a superb novel – perhaps without the scope of “Atonement” but with an interior life, and stories-within-stories, and more books to think of than one can count, and all of this told with Ian McEwan’s signature crystal-clear prose. Bravo!

Sweet Tooth

By Ian McEwan

Nan A. Talese/Doubleday

324 pages, $26.95

Karen Brady is a former News features columnist.