Sweet Tooth is a 2012 novel by Ian McEwan. Set in the 1970s, it tells the story of one woman’s involvement with MI5 and the world of literature. Themes include the balance of power, navigating lies and deceit, and conditional versus unconditional acceptance.

Plot Summary

Serena Frome grows up in a small, uninteresting English city. In the 1960s, her mother encourages her to study mathematics at Cambridge University even though Serena (a keen reader) would rather study literature. She bows to her mother’s request and is one of the only women of her generation to study the subject at Cambridge. However, she struggles at university because she encounters people smarter than her for the first time and literature distracts her, a distraction which leads to a regular literary column in a friend’s student magazine. Her then-boyfriend introduces her to his tutor, an older historian named Tony Canning. Serena and Tony begin a long, secret affair. To hide from his wife, they spend weekends in his country cottage. He teaches her about politics which, as Serena discovers, is actually him grooming her for a position in the British intelligence organization, MI5. He schedules her an interview with the organization for the following September and she accepts because she does not know what else to do with her life. The summer romance ends when Tony angrily accuses Serena of leaving her blouse behind for his wife to find, even though she remembers him telling her to leave the blouse for the housekeeper. Tony breaks up with Serena and she never sees him again.

Serena proceeds with the interview and is accepted into MI5. She is given a low-paid, low-ranking office role which consists mostly of filing other people’s reports. Her colleagues include Shirley Shilling, a friendly working-class girl, and Max Greatorex, an awkward but intelligent man to whom Serena is attracted. Serena spends her evenings socializing with Shirley and spends an increasing amount of time talking with Max. During this time, she discovers that Tony died of terminal cancer. She suspects that he manufactured the argument with her to save her the misery of watching him die. Her increasing paranoia about being followed is compounded when Shirley acts out at work and then they argue about politics while on an assignment. Later, she is made part of a new operation codenamed Sweet Tooth. MI5 wants to fund certain writers who can produce material that they find ideologically suitable. Due to her love of literature, Serena is assigned to a young writer named Thomas Haley. She studies his short stories in preparation and becomes a fan. At the same time, Shirley is fired from her job in a mysterious manner while Max reveals that he is engaged. Serena resents him for hinting that there might be a possibility for romance between them but comes to realize that any relationship is impossible.

Serena visits Haley to make him an offer on behalf of a charity funded by MI5. The charity will pay Haley’s living expenses and allow him to write a novel on any subject he chooses. At a second meeting, Haley accepts, and he and Serena spend the night together. Around this time, Serena learns that Tony was a traitor who passed state secrets to the Soviet Union. Her burgeoning relationship with Haley allows her to deal with the pain of Tony’s death as well as his betrayal. She regularly travels to Brighton to see Haley and spends every weekend with him. In his apartment, she sneaks a peek at his writing but is worried that his short novel will not be approved by her superiors. As they fall in love, Serena worries about telling Haley the truth about her job.

In London, a drunken Max appears on her doorstep one night and reveals that he has ended his engagement to be with Serena. She rejects him. Haley’s short novel is accepted by a publisher and begins to generate interest. He is listed for a prize, though confesses that he does not have any more ideas for novels. They each return to their respective homes for Christmas. Serena is struck by a bout of nostalgia but realizes how much she misses Haley, and she worries that he will find out the truth about her job. When they reunite, they tell one another that they love each other. Haley’s writing career takes off. He gives readings and wins a prestigious prize, but Serena sees him in a pub with Shirley and worries that he is not faithful. He assures her that he loves her. At work, Serena defends Haley’s work, but they are worried about the contents of his novel and her romantic involvement with Haley. However, the truth about Haley and MI5 is published in the press. He and Serena have a big argument and she nearly loses her job. After a period of no contact, she goes to his empty apartment and finds a letter waiting for her. Haley reveals that Max told him the truth about Sweet Tooth and he has turned their experiences into a novel, to be published in the future. Now that they both have their truths laid bare, he asks Serena to marry him.