The narrator of Sweet Tooth is Serena Frome, telling the story of her time employed by MI5 in the early 1970s. She was the pretty daughter of a bishop, pushed by her mother to go to Cambridge to study maths, though she had so little interest in it she spent all her time reading fiction from Valley of the Dolls to Margaret Drabble and A.S. Byatt. At age 21 she has a summer affair with a man of 54. This brings up the first of many wonderful bits in this book:
...I was a little put out to see the first time what 54 years could do to a body. He was sitting on the edge of the bed, bending to remove a sock. His poor naked foot looked like a worn out old shoe. I saw folds of flesh in improbable places, even under his arms. How strange that in my surprise, quickly suppressed, it didn't occur to me that I was looking at my own future. I was 21, what I took to be the norm, taut, smooth, supple, was a transient special case of youth. To me, the old were a separate species, like sparrows or foxes and now what I would give to be 54 again.
Tony (the 54 year old) was the reason she began working for MI5. Serena, though modern and hip in many ways, was happy to work in support of the British tradition. Her love of literature wouldn't seem to be much preparation for this work, but the CIA and MI5 at the time supported writers and artists covertly, so she was given a writer to sign up. This article "Modern Art Was CIA 'Weapon'" in The Guardian in 1995 gives some background about this practice.
Her first assignment was to pose as an employee of a foundation that gives stipends to promising writers; she succeeds and the two promptly begin an affair. Before contacting him, she read and describes to us several of his short stories, giving us some more wonderful little bits. The two of them talk about what fiction each likes and dislikes (she loves Byatt, Drabble, Monica Dickens, Elizabeth Bowen, he loves Muriel Spark's In the Driver's Seat. She explores what fiction is; the connection and its separation from reality.
Asked to give him a good maths story, Serena tells Tom the counterintuitive probability story The Monty Hall problem. For Americans of a certain age (more than 54), this brings up the correct answer supplied by Marilyn vos Savant in her "Ask Marilyn" column in Parade magazine that was rejected by countless readers. (You can read the Wikipedia account for more explanation.) Although Serena wasn't a good mathematician, she had to rewrite Tom's short story that used the concept because he just couldn't get it straight.
I have given short shrift to the overarching story of this novel in favor of the various treasures it offers; my neglect is not because it was unsatisfying or undeserving on that account.
Ian McEwan, Sweet Tooth, Doubleday, 2012, 400 pages (I listened to the audiobook). Available in the UVa and public libraries and from Amazon.