The Oxford Guide to Scandal and Lies

Set at Oxford University during the 1950–51 academic year, the story follows Ginevra (Gin) Bishop, a 22-year-old first-year German student at St. Mildred's College, and Sidney Braithwaite, a 26-year-old Classics student on an ex-serviceman's grant at Swithun College. They clash over a study table in Duke Humfrey's Library, and Professor Michael Leland, a charismatic Classics don and friend of Gin's father, deepens the friction by publicly embarrassing Sidney. That same day, Mr. Tolliver, the elderly librarian at the Bodleian's inquiry desk, behaves oddly while examining a small black notebook.

Months later, Sidney encounters Tolliver at a debate reception, where the librarian hides behind him and makes a cryptic remark about careless librarians before a waiter returns his dropped silver snuffbox. That evening, Sidney and Gin find themselves in a social circle with Donald Craddock, an aristocratic member of the Damocles Club, one of Oxford's exclusive drinking societies. They later hear a cry from the garden and find Tolliver dying on a bench, broken glass at his feet and a gowned figure retreating into the darkness. Tolliver murmurs the German phrase die Krone, meaning the crown, before dying in their arms.

After the funeral, a government intelligence operative called the Rook reveals that Tolliver was murdered with cyanide. Tolliver had been working for the Security Service to identify someone at the university sharing classified information with the Kremlin under the code name Cassius, funneled through Grigor Olenev, a KGB contact running a bookshop in south Oxford. The Rook asks Gin and Sidney to replace Tolliver. Gin is eager. Sidney refuses, haunted by his wartime service as an intelligence asset in occupied France, where a mission ended with the capture of his contact, a Frenchwoman named Amélie, leaving him shot and traumatized. He agrees to a single day of surveillance.

Gin's motivation grows when she learns her father, Viscount Walsingdon, has promised their ancestral home, Chiseldon Park, to the Duke of Allingham, expecting Gin to marry the duke's son Donald to recover it. Furious, Gin resolves to fight her father legally, and the Rook's doubled stipend becomes her lifeline. During surveillance of Olenev's shop, Gin breaks into an adjacent building and discovers Tolliver's stolen notebook in a hidden desk compartment, memorizing four coded sentences. She reveals her desperation to Sidney, and moved by her honesty, he agrees to the partnership.

Together they decode the sentences using Caesar shift ciphers, a method in which each letter is shifted by a set number. The results produce four suspects: Marion Kirk, a postgraduate who writes for the student paper The Blue alongside Gin's close friend Iris Finchley; Lewis Hughes, an American postgraduate; and two Classics tutors, Dr. Samuel Neville and Dr. Jacqueline Watkins.

Gin infiltrates The Blue's offices and observes Kirk's fierce opposition to the Damocles Club. At the chess club, she earns a game against Neville, who reveals he attended the 1948 World Chess Championship in Moscow. When Gin casually mentions die Krone, Neville's hand falters on a chess piece. She later finds a partially redacted Russian letter hidden in one of his books. Sidney, meanwhile, joins Watkins's seminar, observes both Watkins and Neville visiting Olenev's shop, and follows Hughes to Tolliver's cottage.

At Tolliver's cottage, Gin and Sidney discover an appointment diary with coded entries and, beneath a loose floorboard, newspaper clippings linking the suspects to events such as Watkins at a cottage hospital and a student named Quintin Jones who died in a mysterious incident. Through Iris, Gin later gains access to Kirk's room and finds walls plastered with Damocles Club clippings centered on Jones's death, along with Communist literature identical to booklets in Olenev's desk.

At a party for Leland's memoir, Neville gives a speech about their shared imprisonment at Vosburg, a German castle used as a prisoner-of-war camp, describing how Leland unmasked a traitor nicknamed die Krone: a soldier named Robert Crowne. Masked intruders storm the party, and Sidney rescues Gin when she is nearly strangled in the chaos. The Rook later provides Crowne's history: Expelled from Oxford after a sconcing incident (a drinking penalty game) caused a student's death, Crowne enlisted, served as Neville's orderly at Vosburg, was accused of being the German spy based on Neville's testimony, and died by suicide after the war.

During the Dramatic Society's production of Julius Caesar, Gin and Sidney search Neville's office and find a Soviet visa application suggesting he plans to defect. They also discover Watkins has been stealing colleagues' books to sell to Olenev. A colleague at The Blue gives Gin Kirk's forwarding address: care of Patricia Crowne, Robert Crowne's elderly aunt, in Shropshire, confirming Kirk is Crowne's niece.

At the Damocles Club's gala at Foxley Hall, Donald's family estate, Watkins tells Sidney that Neville visits Olenev not to pass intelligence but to exchange love letters with a Russian woman whose family monitors her correspondence. Donald inadvertently provides a crucial clue, correcting the German word from the Vosburg story to die Zahnkrone. Gin realizes Zahnkrone means "tooth crown," pointing not to Robert Crowne but to someone with a gold tooth: Professor Leland. Neville and Kirk piece together that Leland was the real German informant, named for his gold molar, and that he framed Crowne by planting evidence. Cornered, Leland draws a pistol and flees after a struggle that leaves Sidney concussed.

Gin takes the group to Chiseldon Park. Sidney confides the full story of his wartime trauma to Gin. They later nearly kiss in the garden maze before the butler interrupts. Gin confronts her father, who reveals she is not his biological daughter; her mother was pregnant by another man when she married the viscount. Though shaken, Gin feels relief that his lifelong coldness was never her fault and severs the relationship.

Hughes reveals he has been working for American intelligence, also tracking the informant. The Rook reports Leland has vanished, and Gin guesses he is hiding at his country cottage nearby. At the cottage, they overpower Leland and extract a taped confession about Vosburg, but Leland appears genuinely confused about the current Kremlin leak. Sidney notices a planted note written left-handed, while Leland is right-handed. Gin deduces the true informant: Dr. Watkins had been Robert Crowne's fiancée when she worked as a nurse near his home. After Crowne's death, Watkins came to Oxford, began selling stolen books to Olenev, and was recruited by the KGB. She chose the code name Cassius after the role Leland always played in the Dramatic Society, framing him for a second betrayal. After Gin disarms Watkins, police storm the cottage and arrest both Watkins and Leland. Watkins confesses to murdering Tolliver by poisoning his snuffbox with cyanide.

The Rook pays their stipend and provides a security-box key. At a London bank, Gin's envelope contains the deed to an Oxford cottage inherited from her mother, giving her independence from the viscount. Sidney's envelope holds a letter from Amélie, revealed to be an Englishwoman named Amelia who is alive and well, releasing him from years of guilt. The novel closes from the Rook's perspective: He receives a warning call about recruiting Gin, with the caller insisting that family should be off-limits, hinting at deeper secrets about Gin's parentage and future entanglements with the intelligence world.