“Sweet Tooth” begins as any other ’70s era British spy novel with promises of intrigue, perilous love and ample suspense. But in the capable hands of author Ian McEwan (“Atonement,” “On Chesil Beach”), the story becomes something entirely unexpected. It can be categorized as meta-fiction, which sounds like trendy label but is completely fitting for this multifaceted work of fiction. Once the spy-story veneer fades, the reader will come to realize that “Sweet Tooth” is a meditative novel concerning the power of fiction and the toils of writing.

Serena Frome (“rhymes with plume”) jumps into the story by relaying the novel’s plot from start to finish. “Within eighteen months of joining [The British Security Service] I was sacked, having disgraced myself and ruined my lover, though he certainly had a hand in his own undoing.” So begins Serena’s deliberation, which is essentially a reiteration of how she disgraced herself and how the lives of herself and her lover came apart.

In her youth, Serena was encouraged by her quietly feminist mother to study mathematics at Cambridge, where she struggled to succeed. Her true passion, however, lay in fiction, and Serena’s voracious reading gradually turns her onto anti-Communist ideals in the midst of Cold War turbulence in the ’70s. She writes about communism for a literary journal and garners the attention of the aging Professor Canning. The two engage in a summer-long affair until Canning unceremoniously dumps Serena, but not without recruiting her to MI5, the British Security Service.

At MI5, Serena works as a glorified secretary until her love for literature has her summoned to a room full of haughty men who offer her a mission that involves recruiting authors and journalists who would perpetuate the ideals of MI5 through their writing. Codenamed Sweet Tooth, the mission would require Serena to approach struggling writer Tom Haley with a hefty stipend from her “arts foundation” and work closely with him, while ensuring that Tom never finds out where the money is coming from. In short, it’s a novelist’s dream.

This is the point where the story gains momentum. Up until this point, Serena’s narrative reads too passively to capture the true essence of a spy novel, and it leaves the reader unclear on where things are headed. But as Serena looks over Tom’s work and then meets the man himself, the novel’s espionage façade finally peels away to reveal that “Sweet Tooth” is a literary love story. And as Serena and Tom fall for each other, she must grapple with the knowledge that she cannot—but eventually must—tell Tom about the truth about her line of employment.

McEwan utilizes the correlation between reading and writing as a parallel through which he explores the relationship between Serena and Tom, and he packs authors and editors from his own life (notably Martin Amis, Tom Maschler and Ian Hamilton) into the story’s third act. The closing third of the novel takes such an enjoyable jaunt into fiction and meta-commentary that I wish McEwan had introduced Serena and Tom’s relationship earlier in the novel; its earlier pages feel bogged down by meandering narrative and painstakingly researched history lessons about espionage in the 1970s. McEwan’s prose shines as the novel reaches its climax (he writes, “Love doesn’t grow at a steady rate, but advances in surges, bolts, wild leaps,” which I’m sure will become a popularly reblogged quote on micro-blogs like Tumblr).

The novel’s final pages are breathtakingly surprising and demand a second reading from its audience — if anyone can get through the dull first act again. Despite my few complaints, “Sweet Tooth” is a worthwhile weekend read, and its twist ending is indeed quite sweet.

Rating: 3.5 stars