Lethal White

Lethal White is preceded by The Cuckoo's Calling, The Silkworm, and Career of Evil;[6][7][4][8] there are tentative plans to follow it with at least five more stories.[9][10][11][12] Rowling announced the completion of the manuscript on 23 March 2018, after approximately two years of writing,[2][13][14] and the book was released on 18 September 2018.[5] Lethal White follows the private detective Cormoran Strike and his partner Robin Ellacott.[15][13] The story begins with a Prologue following immediately after the conclusion of Career of Evil detailing events taking place at Robin's wedding reception.

At Robin Ellacott's marriage to Matthew Cunliffe, Cormoran Strike's capture of the Shacklewell Ripper the night before is already widely known, except by Robin. When Strike tells her that he had been trying to contact her during the week, she realizes that Matthew had deleted Strike's messages, which results in a serious row between the new spouses. Before Strike leaves, Robin accepts his offer of working as a salaried partner in the detective agency.

One year later, Strike has grown his detective agency to the point where he needs to hire more investigators. He receives an unsolicited visit from Billy Knight, a young man with a history of mental illness who claims to have witnessed a murder and the burial of the body in woodland some years before, but is unable to provide any details before he runs out of Strike's office. While trying to establish Billy's identity, Strike meets Billy's older brother Jimmy and Jimmy's girlfriend Flick, radical left-wing activists who claim Billy is unstable and unreliable.

Strike's meeting with Jimmy draws the attention of Jasper Chiswell, the Minister for Culture, whom Strike knew from investigating the combat death of his son Freddie. Chiswell has been blackmailed by Jimmy and hires Strike to investigate; he identifies Geraint Winn, the husband of a political enemy, as Jimmy's likely partner. Chiswell does not reveal what he is accused of, but claims that what he did was legal "at the time". Robin then goes undercover in Chiswell's office to carry out surveillance on Geraint, whose wife has a neighboring office, although the undercover assignment places more strain on her marriage. She meets Chiswell's family who works for him: daughter Isabella, illegitimate son Raphael, and second wife Kinvara. By bugging Geraint's office, Robin discovers that Geraint has been embezzling money from his wife's charities, and Chiswell uses this knowledge to stop Geraint's blackmail.

Chiswell summons Strike and Robin to a house that he keeps in the city for business, perhaps intending to fire them, but on arrival, they find Chiswell's body, apparently dead from suffocation and an overdose of anti-depressants. The Metropolitan Police rule his death a suicide, but Isabella is convinced that Kinvara is responsible, again hiring Strike to investigate. Strike believes that the mysterious blackmail is connected to Chiswell's death and eventually learns that Chiswell and Jack Knight, Jimmy and Billy's late father, built gallows for export before the European Union banned the export of torture and execution equipment from member states. Two of these gallows were sold to Zimbabwe, where one was stolen by rebels and used in the murder of a British teenager. The gallows could be traced to Chiswell because Billy had carved the nearby White Horse of Uffington into it.

Meanwhile, Robin continues to struggle with post-traumatic stress disorder a year after her encounter with the Shacklewell Ripper, while Matthew continues to interfere with her work. But Robin separates from Matthew and moves out when she finds proof that he has been having a long-term affair throughout most of their relationship. She intends to seek a divorce when she can afford it and moves in first with her friend Vanessa Ekwensi, then with Strike's friends Nick and Ilsa Herbert. Strike counsels her, drawing on his own experience of losing a leg. Strike's ex-girlfriend Charlotte Ross, now married and pregnant, reappears and unsuccessfully pursues Strike.

Strike learns that Chiswell wrote Kinvara out of his will and bequeathed everything to his ten-year-old grandson, while allowing Kinvara only to live on the family estate for the rest of her life. However, Chiswell carelessly omitted certain items from the will, including a diamond necklace that is the family's last item of real value, meaning that legally such items may be Kinvara's. Strike suspects there are other items of value Chiswell overlooked. He is drawn to a supposedly-worthless painting titled Mare Mourning and discovers that it may be a lost George Stubbs artwork depicting a mare mourning a foal that died of lethal white syndrome. If its provenance were to be established, it would probably be worth over £20 million. Strike can then identify Chiswell's killer: Raphael, who had had never been accepted by the family but had worked for an art dealer. Raphael had tipped off Flick about a cleaning job at Chiswell's, expecting that she would find out about the gallows sales and tell Jimmy, who then demanded 50% of the profits. Raphael also seduced and conspired with Kinvara to kill Chiswell; when Flick learned that Chiswell had inadvertently found out about the affair and also had begun to investigate Mare Mourning, Raphael killed Chiswell at once.

Kinvara confesses, but Raphael sends Robin texts purporting to be from Matthew, luring her into a trap. He keeps her alive to interrogate her about the investigation before disappearing; Robin stalls for time by outlining everything in detail, even describing his un-executed plan to kill Kinvara. Strike realizes Raphael's duplicity when he notices that the text messages to Robin came from a disposable mobile phone used in the blackmail case. The police trace the phone and raid the houseboat on which Raphael has Robin, arresting him just as he has decided to terminate her and flee. In the aftermath, Strike, Robin and Isabella meet Billy to discuss the "murder" he witnessed. Isabella and Strike reveal that Billy was drugged by Freddie and Jimmy. Billy then saw Freddie choke a young Raphael until he passed out, followed by the burial of a small horse that Freddie had killed in a separate act of cruelty, which Strike's crew has dug up. Strike and Robin then leave together.

• Cormoran Strike – A war veteran who was honourably discharged after losing half of his leg in a bomb attack. He has since become a private detective. He is a minor celebrity, thanks in part to his rock star father and his solving of high-profile murders.
• Robin Ellacott – Strike's secretary who completed a course in criminal investigation, paid for by Strike, who becomes his business partner while at her wedding. She is a survivor of a rape and attempted murder and is extremely sensitive regarding sex crimes.
• Matthew Cunliffe – Robin's longtime boyfriend and new husband.
• Charlotte Campbell Ross – Strike's ex-girlfriend who is currently married and expecting.
• Nick Herbert – An old friend of Strike's, with whom he occasionally stays to avoid publicity.
• Ilsa Herbert – An old classmate of Strike's, now married to Nick.
• Billy Knight - A young man who claims to have witnessed a murder some years prior.
• Jimmy Knight - Billy's brother, a left-wing activist.
• Flick Purdue - Jimmy's girlfriend and fellow activist.
• Jasper Chiswell - A mercurial and scandal-plagued Member of Parliament serving as the Minister for Culture.
• Freddie Chiswell - Jasper's late son, whose death in combat was investigated by Strike.
• Isabella Chiswell - Jasper's hard-working but under-appreciated daughter.
• Raphael - Jasper's illegitimate son, who was recently released from prison after killing a woman while driving under the influence.
• Kinvara Chiswell - Jasper's young, unstable, histrionic second wife.
• Geraint Winn - The husband of Minister for Sport Della Winn, one of Jasper's political enemies.
• Vanessa Ekwensi - A police detective who befriends Robin.

Lethal White was adapted as part of the television series starring Tom Burke as Cormoran Strike and Holliday Grainger as Robin Ellacott.[16] Filming began in September 2019. The first episode was broadcast on 30th August 2020.