Criminal barrister Leila Reynolds arrives at her legal offices, known as chambers, for a party celebrating the 59th birthday of Chester Vernon, the head of chambers. Her senior clerk, Jim, stops her to share two pieces of news. First, she has been praised in the Legal 500 as a “future bright star and KC in the making” (9). Second, he hands her a new brief to defend Jack Millman, who is accused of murdering Judge Anton Smythe.

Leila is stunned, as she has never handled a murder trial and has previously defended Jack Millman unsuccessfully. Jim insists she must take the case because Jack specifically requested her. He also reveals that the solicitor firm is the dubious Jessops. To Leila’s horror, she learns the prosecuting King’s Counsel (KC) is Julian Kesler—her former mentor and current husband.

At the party, Leila confronts Julian, who is unconcerned, viewing the high-profile case as a career opportunity for both of them. He dismisses her anxiety, noting the evidence against Jack looks damning and he expects a quick guilty plea. Other barristers gossip about Leila, with some implying she only got the case because of her husband. Leila overhears them discussing that the murder occurred at Jack’s flat above the Temptation club, an elite and illicit men’s club in Durham. She speaks with Chester’s young wife, Demi Vernon, who acts evasive when asked if she knew the victim. Throughout the evening, Leila notices that Demi deliberately avoids speaking to Julian.

The narrative shifts to an anonymous first-person narrator, identified as “Witness X.” She reflects on her first rule for survival: “Don’t Get Caught” (23), acknowledging that she is in serious trouble and lives in fear of being discovered. After reading a news report about the arrest of a 32-year-old man for Judge Smythe’s murder, the narrator recalls a recent dangerous affair and a set of 12 “toxic laws” taught to her by an unnamed man. Fearing that the murder investigation will uncover her connection to the victim, Witness X concludes she needs the help of a woman she had hoped to be free of.

Leila and Julian take a weekend trip to Barkenfield Lodge for his birthday, agreeing to set the case aside. Over an expensive bottle of wine, Julian admits he used a connection to secure Leila her complimentary Legal 500 quote, which disappoints her. He urges her to embrace the advantages of being married to a senior KC and to prove her merit by winning the trial. Despite their agreement not to talk about the case, he begins probing for information about her client, Jack Millman. Later, a gift is delivered to their cabin: another bottle of the same expensive wine with a card reading, “Hell is empty and all the devils are here. Happy Birthday, J” (34). Julian becomes unsettled, demanding to know who Leila told about their trip, though he quickly catches himself and apologizes.

Leila and solicitor Davina Jessop meet their client, Jack Millman, in the court cells. Jack confirms he will plead not guilty but refuses to discuss the night of the crime, insisting he will only explain what happened from the witness box at trial. However, he claims his phone, which contained sensitive information, was stolen just before the murder. Jack cryptically states that the case “goes high up” (42) and that he is protecting others.

On learning that Julian is the prosecutor, Jack decides to retain Leila, stating she is the only lawyer he trusts after their previous case together. At the brief court hearing, Leila sees Anton Smythe’s grieving wife and son in the public gallery.

Leila attends the memorial service for Judge Anton Smythe at Durham Crown Court, where she feels out of place. After the service, she speaks with Keiran Fox, Anton’s former pupil, who mentions Anton had always tried to talk him into returning to the Bar. They are joined by Keiran’s wife, Sienna Fox, who is Julian’s ex-wife. When Julian arrives, the atmosphere grows tense. Julian mocks Keiran for never reaching his full potential, provoking Keiran to swear at him and imply that Julian’s relationship with Leila began inappropriately. Afterward, Leila confronts Julian about his hostility. He admits his anger stems from Sienna having had an affair with Keiran years ago and confesses he worries Leila might do the same. She reassures him of her loyalty.

Leila gives an inspirational Q&A session at a local school for her legal blog, Chats at the Bar. She encourages students from working-class backgrounds and speaks out against sexism. During the session, an unseen woman asks a series of hostile questions, insinuating Leila used sexual favors and her marriage to a KC to advance her career. The host cuts the questioner off.

As Leila leaves later that night, she walks through the dark, nearly empty car park and sees a hooded figure standing beside her car. When her car’s lights flash as she unlocks it, the figure is startled and quickly walks away into the darkness, leaving Leila deeply unsettled.

Leila chooses not to tell Julian about the hooded figure to avoid causing drama. The following afternoon, she accepts an invitation for a drink from Chester Vernon, her head of chambers. Chester, who is drunk, confides that he suspects Demi is having an affair, describing her behavior as distant and erratic. During the conversation, he places his hand on Leila’s thigh. She gives him a cold stare, and he immediately apologizes.

The narrator, Witness X, discusses her second rule: “Become Someone’s Addiction” (65). She recalls how her father taught her to manipulate men by becoming an elusive fantasy. This led to a pattern of destructive behavior, exemplified by a past relationship with a kind man named Declan, whom the narrator deliberately cheated on and emotionally destroyed simply to feel a sense of power. The narrator reflects that if her husband discovers her latest affair, he will kill her.

Leila and Davina review the prosecution’s evidence against Jack Millman. The murder weapon was a ten-kilogram kettlebell, but no prints were found on it. The victim’s fingerprints were on a kitchen knife, but Jack had no knife injuries. Forensic evidence includes fibers from Anton Smythe’s clothing on Jack’s shirt, Jack’s fresh semen on the sofa, and seven strands of unidentified female hair. Davina suggests she meet with Jack alone to get him to talk, but Leila firmly refuses.

Later, Leila receives a hostile Instagram message from a new account, @JustAnotherDumbBlonde. The sender reveals that she attended Leila’s recent talk at a local school and challenges the authenticity of Leila’s self-presentation as a feminist, working-class role model. The message mocks Leila’s “sad childhood,” accuses her of attending an elite boarding school, and alludes to instances of sexual impropriety, warning that her deceptions put her present client at risk.

In a flashback to February 8, 2019, a more junior Leila takes on an undesirable last-minute case representing Jack Millman, then a 27-year-old bouncer at the Temptation Club. He is charged with grievous bodily harm for punching a notorious criminal, Tony Flanagan. Jack claims he acted to defend a young hostess, Mia Woods, from sexual assault. The case is complicated because Flanagan is a rival of the club’s owner, Eddie Sorrington, and may intimidate Mia to prevent her from testifying. Torn between keeping Jack’s defense secret and officially disclosing it, Leila follows her mentor Julian’s advice and serves a full defense statement that provides Jack’s entire account of events before the trial. Leila’s gut feeling that she made the wrong decision is confirmed when Jack is convicted and labeled a grass.

Witness X discusses their third rule: “Knowledge Is Power” (83). She explains that her father taught her to survive by identifying and exploiting others’ emotional weaknesses before she could be exploited herself. She reflects that both Jack Millman and Anton Smythe are in their current predicaments because they failed to guard their own vulnerabilities. The narrator is fiercely protective of the safe life she has built and resolves to use the manipulative tools she learned from her abusive father to protect it.

Troubled by the anonymous Instagram message, Leila makes her weekly Friday visit to her mother-in-law, Audrey, who is 78 and in the early stages of dementia. Leila is concerned to find Audrey has once again left her front door unlocked. During their fish-and-chips dinner, Audrey has a moment of seeming lucidity and tells Leila she knows her “dirty secret.” Leila panics, but Audrey reveals she is only referring to the fact that Leila dyes her hair blonde. Relieved, Leila tidies the house, her anxiety returning as she considers how vulnerable Audrey is living alone in the large, unlocked property filled with valuables.