This is a Reader's book. It is about writing, about words, and about the power of words. It is about the pen being wielded in the same battlefields as the sword, and sometimes with the same amount of ignorance.
Serena is a young woman, and a babe in the woods when it comes to being an "operative" in MI5 back in the early 70s. She stumbles into her new career and is thrilled with the glamour she thinks must surely be just around the corner when one works for that secret department. She eagerly hopes for an assignment that will reach beyond the usual fate for MI5's women of the drudgery of secretarial work. So she embraces the chance to recruit, without his knowing, a young writer into a program secretly funded by MI5 to encourage literary culture favourable to their government's politics. It was a way to use unsuspecting writers to create the state's propaganda. In this world of intelligence gathering, there seems to be very little intelligence and a great deal of petty office politicking and paper polishing.
Serena is annoyingly simple and self-absorbed, and remarkably passive, to the point where all sympathy is eroded and one impatiently awaits and hopes for a spectacular downfall. She is just about the least convincing character of the book.
Literature and the publishing world have prominent roles, and there is frequent name-dropping of real authors, including McEwan's friend Martin Amis who has non-speaking parts in the book. McEwan is having a bit of fun with other background scenes too. One of the women in the MI5 office is moving up fast through the ranks, and Serena notes that eventually the woman would become director of MI5. Her name is Millie Trimingham -- note the similar rhythm and sounds to the real life Stella Rimington, who herself was moving up the ranks in that time and went to become director. And then on p 97, one of the characters says, "...sooner or later one of our own is going to be chairing this new Booker Prize committee." I imagine a mild grin on McEwan's face as he types that.
There was also a bit in one of the writer's stories within the book that was remarkably similar to the premise of the movie "Lars and the Real Girl". I would like to find some interviews with McEwan to see if he talks about some of these things.
It was interesting to learn that the setting of this novel is not so fictional. There have always been various arms-length or secret funding of arts organisations and individuals that will promote views sympathetic to those of the ruling classes. McEwan's publisher Random House has an interesting essay about this http://www.randomhouse.ca/hazlitt/feature/spook-stories-all-writers-are-spies , and they describe the book as a "semi-autobiographical mash-up".
The opening chapters and the final chapter are the best of the book.