Thinks...

Set at the fictional University of Gloucester, a self-contained English campus that the protagonist compares to an artificial holiday village, the novel alternates between the private thoughts of two characters whose intellectual sparring and growing attraction drive the story forward.

Ralph Messenger, a charismatic professor and director of the university's Holt Belling Centre for Cognitive Science, opens the novel by recording his thoughts into a pocket tape recorder on a Sunday morning in February 1997. His monologue, an experiment in capturing the raw texture of consciousness, ranges across sexual memories, complaints about his wife Carrie, reflections on William James's metaphors for thought, and observations of the rain-soaked campus. He spots a woman walking alone and identifies her as Helen Reed, a recently widowed novelist who has just arrived as Writer in Residence.

Helen's perspective, rendered through her private journal, reveals a woman barely holding herself together. Still grieving for her husband Martin, who worked at the BBC and died suddenly of a brain haemorrhage a year earlier, she finds the campus isolating and her new teaching post intimidating. She has been unable to write fiction since Martin's death. At a dinner party hosted by Jasper Richmond, head of the English department, and his wife Marianne, Helen meets Ralph and is struck by his commanding presence. She also accidentally witnesses him kissing Marianne passionately in the kitchen, establishing early the novel's preoccupation with the gap between public behavior and private desire.

Ralph and Helen begin meeting for lunch and engaging in spirited debate. He argues that consciousness is a problem science will eventually solve, that the self is a fiction, and that there is no soul or afterlife. Helen counters that literature has been representing consciousness for two centuries, quoting the opening of Henry James's The Wings of the Dove from memory. Ralph dismisses literary fiction as "folk psychology"; Helen retorts that cognitive science could tell us nothing about a real person worth knowing. He takes her on a tour of his Centre, a round building whose mirror-glass walls symbolize the privacy of consciousness: One can see out but not in. Inside, a mural illustrates famous thought experiments, including Thomas Nagel's argument about what it is like to be a bat, Searle's Chinese Room (which asks whether manipulating symbols according to rules constitutes genuine understanding), and Frank Jackson's scenario of a color scientist raised in a monochrome environment. These ideas feed into Helen's teaching. She assigns her creative writing students exercises based on the thought experiments, and they produce clever literary parodies.

Helen is drawn into the orbit of the Messenger family. Carrie, Ralph's wealthy American wife, befriends her, inviting her to their Cheltenham house and their country cottage, Horseshoes. There, after a debate about the soul in the outdoor hot tub, Ralph kisses Helen in a darkened staircase. She does not resist but resolves not to have an affair, citing her friendship with Carrie and her objection to adultery. At Ralph's birthday party, he leads her upstairs to his study, shows her a framed Darwin quotation reading "Crying is a puzzler," and asks for a kiss. Helen refuses, revealing she saw him kissing Marianne. Ralph claims that arrangement is over. He persists: Over an elaborate lunch Helen prepares at her campus maisonette, he tells her he is "falling in love" with her and proposes they go to bed. Helen refuses again, admitting in her journal that the refusal was "a close call." Ralph then proposes they exchange their private journals as an experiment in mutual transparency; Helen declines, detecting something "distinctly Faustian" about the offer.

Two revelations shift Helen's moral calculus. She reads further chapters of a novel by Sandra Pickering, one of her students, and recognizes with horror that the intimate sexual details replicate her own experience with Martin. Sandra confirms a six-month affair with Martin while working as his research assistant at the BBC, adding that she "wasn't the first, or the last." Helen confides in Carrie during a trip to the Droitwich Brine Baths. Carrie reciprocates with her own romantic history and advises Helen that Martin's refusal to leave his family proves he loved her. Floating in the brine, Helen resolves she will never weep for Martin again. The second revelation comes on a solo outing to Ledbury, where Helen discovers Carrie lunching with Nicholas Beck, a Professor of Fine Art widely assumed to be celibate and gay, and witnesses Beck kiss Carrie unmistakably as a lover. Knowing that Carrie, too, has strayed dissolves Helen's principled objection to adultery.

When Carrie's father has a heart attack and she flies to California, Helen and Ralph begin an intense three-week affair, meeting at Horseshoes, at the Messengers' Pittville house while the children sleep, on the prehistoric barrow at Belas Knap, and at a London hotel. Helen writes about the experience in the third person, as if unable to examine her own conduct directly.

The affair is interrupted by a medical crisis. Ralph's GP discovers a lump on his liver, and tests raise the possibility of cancer. Ralph privately resolves that if the diagnosis is terminal, he will end his own life, and asks Helen for help. She refuses but promises secrecy. Other problems converge: The student newspaper links the Centre's research to the Ministry of Defence, threatening funding; a police detective reveals someone in the Centre is downloading child pornography; and Ludmila Lisk, a young Czech researcher Ralph slept with in Prague, threatens to publicize their encounter unless he secures her a conference spot.

Carrie locates Mr Halib, England's top liver surgeon, who suspects a hydatid cyst, a benign condition caused by ingesting tapeworm eggs, plausible given Ralph's teenage summers on a Yorkshire sheep farm. A blood test confirms the diagnosis during the final day of the International Conference on Consciousness Studies. At the same moment, Detective Sergeant Agnew confronts Professor Douglas C. Douglass, Ralph's colleague, about examining his computer. Douglass excuses himself and hangs himself with a computer lead; hundreds of photographs of children are later found in his office. Ralph conceals the suicide long enough for Helen to deliver the closing address, using Andrew Marvell's poem "The Garden" to argue for the irreducibility of consciousness and the value of literary representation against scientific reductionism.

Ralph decides to preserve his marriage. On the Thursday before Helen's departure, he lets himself into her maisonette and reads her journal on her laptop, discovering her account of Carrie and Beck's kiss. Helen arrives, realizes what he has done, and orders him to leave. Driving home, Ralph's rage at Carrie's infidelity cools as he calculates the consequences: counter-accusations, divorce, financial loss. He says nothing.

Helen leaves the campus the next morning, enacting the escape she fantasized about in her first weeks. Back in London, she picks up a photograph of Martin, forgives him, and weeps one last time. The novel closes with an omniscient summary: Ralph has a successful operation, becomes more subdued, and receives a CBE (Commander of the Order of the British Empire). Carrie ends her affair with Beck and takes up sculpture. Helen begins a relationship with a literary biographer and publishes a new novel set at a greenfields university, entitled Crying is a Puzzler.