Here are the main points:
- The story told by Serena Frome. a rather gauche young woman who is addicted to "middlebrow" novels which she "speed-reads," reads itself like just such a middlebrow novel, until McEwan turns the tables on his readers with a highbrow, postmodern trick. The sweet story is about Serena's loves (Jeremy who turns out to be homosexual, the much older professorial Tony who dumps her to protect his marriage, and finally the young author Tom), her entrance into MI5 and her task to recruit the writer Tom Haley. She offers him a stipend "enough to keep a chap from having to do a day job for a year or two, even three." As happens in all novels she reads, she finally "gets" the right guy, although she fails miserably in her spy job.
- The story of Britain (and wider, Europe) in the early 1970s: malfunctioning of the state (like a rotten tooth), terrorism threats, a war in the Middle East and the First Oil Crisis, the Cold War and rampant leftism among the young.
- A tongue in cheek "Tinker Tailor" story of MI5 - the misogynist culture, the complicated secrecy about nothing, the silliness of the Sweet Tooth project.
- The world of literature when McEwan himself was writing his first short stories - his colleagues as Martin Amis, his publisher, etc. Several of McEwan's early stories are paraphrased, the dystopian novel Tom Haley produces as part of the MI5 program (so not at all what they wanted!) is also based on such a story.