My Husband's Wife

The novel opens with a prologue set in October 2015: An unnamed narrator lies bleeding on a kitchen floor after a stabbing, gazing up at a painting of a white house in Italy. A newspaper clipping reports that artist Ed Macdonald has been found stabbed to death in his home. The story then jumps back fifteen years, alternating between two narrators whose lives become fatally intertwined.

In late September 2000, Lily Hall, a newly married twenty-five-year-old solicitor, returns from her honeymoon in Sicily with her husband Ed Macdonald, a graphic designer who dreams of becoming a full-time artist. Her boss transfers her from employment law to criminal defense, assigning her the pro bono appeal of Joe Thomas, an insurance salesman convicted of murdering his girlfriend Sarah Evans by pushing her into a scalding bath. Joe is intelligent and manipulative, setting Lily puzzles rather than explaining his case directly. Lily is unsettled by his ability to deduce personal details about her but also drawn to him.

That same morning, Lily passes her neighbor Francesca Cavoletti, an Italian single mother, and Francesca's nine-year-old daughter Carla. Carla is bullied at school for her appearance and Italian-sounding name. After Carla is injured at school, Lily takes her to the hospital and begins looking after her on weekends while Francesca spends time with "Larry," a married man who pays their bills. Ed begins sketching Carla, captivated by her as a subject.

Lily enlists Ross Edwards, an actuary she meets at a party, to decode Joe's puzzles, which turn out to reference faulty boilers linked to irregular water temperatures. She recruits Tony Gordon, a famous barrister, to handle Joe's appeal. The case draws threats: Lily receives menacing notes, has her bag stolen, and her parents' horse is poisoned. She secretly gives Joe sticker albums belonging to her deceased adopted brother Daniel, crossing a serious professional boundary.

Lily's marriage is strained from the start. Their honeymoon was a disaster because Lily struggled with physical intimacy, a difficulty rooted in her past. At Christmas with Ed's family, his sister-in-law Sophie reveals a family trust requiring all grandchildren to marry by thirty or forfeit their inheritance. Ed married Lily partly for financial reasons, and his ex-girlfriend Davina broke off her engagement to another man while Ed and Lily were on their honeymoon. Despite feeling betrayed, Lily agrees to try again.

Meanwhile, Carla learns to use leverage, blackmailing Larry into securing her a place at a convent school by threatening to reveal she saw him kissing another woman. She initially thrives there but is ostracized when a classmate's family discovers Francesca is an unmarried mother.

The retrial succeeds and Joe is acquitted. Lily then discovers that "Larry" is actually Tony Gordon, her barrister colleague, living a double life. She confronts them furiously, and Carla reveals Larry's infidelity with yet another woman. Without Larry's financial support, Francesca and Carla return to Italy.

After the acquittal, Joe confesses the truth during a walk across Hampstead Heath: He is genuinely guilty. He turned up the boiler, pushed Sarah into the scalding water, and orchestrated the threats against Lily through prison contacts to manipulate her into fighting harder. Lily is horrified, but in her vulnerable state she has a sexual encounter with Joe that she deeply regrets. Four weeks later, she discovers she is pregnant and sleeps with Ed so the child could plausibly be his. She never tells Ed about Joe.

Part Two jumps to autumn 2013. Lily and Ed have an eleven-year-old son, Tom, who has Asperger's syndrome and lives with Lily's parents in Devon during the week because his challenging behavior became too difficult to manage at home. Ed has opened a gallery after his childhood portrait of Carla, The Italian Girl, sold to an anonymous buyer for a large sum. Lily has become a partner at her firm.

Carla, now nearly twenty-three, returns to London to study law, motivated by resentment and a desire to reclaim what she believes she is owed. She reconnects with Ed, who is eager to paint her again. Lily is wary, having secretly intercepted letters Carla sent from Italy requesting money. Carla visits the dying Tony Gordon in a hospice and delivers Francesca's message that she still loves him. Tony weeps and dies shortly afterward.

Joe Thomas, who has been watching Lily for years, demands a paternity test for Tom, insisting the boy is his. Lily refuses. Joe reveals he has been sending her anonymous tips to help her win cases; when she stops accepting his help, her success rate drops.

After a fire at Carla's hostel, Ed invites her to stay. He paints Carla again, generating enormous press attention, and the two begin an affair. Lily discovers them after Joe tips her off. Ed files for divorce, and Lily moves to Devon.

On the Devon promenade, Joe confronts Lily again about paternity. During the encounter, Lily's old house key falls from her pocket, and Joe keeps it. Lily tells him the key belongs to the house where Ed and Carla now live. When Joe suggests he could frighten Carla, Lily replies that she would not want Carla hurt, just scared perhaps, before running away, horrified by what she has implied.

Carla marries Ed but finds herself trapped. Ed becomes controlling and drinks heavily, deeply in debt. Carla becomes pregnant, and their daughter Poppy is born prematurely. On the day of the birth, Ed reveals that Francesca has died of cancer in Italy. Francesca had hidden her illness from Carla, and her death devastates Carla.

During an argument, Ed grabs a carving knife. Carla stabs him in the thigh in self-defense. Joe Thomas appears at the open front door. Carla flees into the night, discarding her bloody washing-up gloves in a hedge. Joe finds Ed alive with the knife in his leg and pulls it out, causing Ed to bleed to death.

Carla is arrested and asks Lily to represent her. Lily agrees, secretly hoping Carla will be convicted so the police will never investigate Joe and discover Lily's role in providing the key. She deliberately selects an inexperienced barrister, but her plan backfires when the jury acquits Carla.

Joe sends Lily the bloody gloves, which he retrieved from the bushes, with Lily's old key tucked inside. Lily confronts Carla at the old house, threatening retrial under new double jeopardy laws. Carla pushes Lily, badly injuring her, and destroys the gloves. Joe arrives, finds Lily hurt, and attacks Carla with a knife, leaving her permanently disfigured.

In two subsequent trials, Carla is convicted of Ed's murder and Joe is convicted of assaulting Carla and of being an accessory. Joe falsely testifies that Carla hired him as a hit man, a lie that secures her conviction while shielding Lily from exposure. Both receive life sentences.

Lily confides her full history to Ross: Her adopted brother Daniel, with whom she had a forbidden romantic relationship as a teenager, hanged himself after Lily went on a date with another boy. This guilt has shaped Lily's difficulty with intimacy and her attraction to dangerous men like Joe.

In a final prison visit, Joe reveals the truth: He never needed Lily's key because the door was already open. He returned it inside the gloves. He confirms he pulled the knife from Ed's leg, causing his death, and lied about Carla hiring him to protect Lily.

The epilogue, set in summer 2017, finds Lily marrying Ross, who has confessed his own dark secret about contributing to a friend's death as a teenager. Tom attends with Alice, a school friend who shares his challenges. Carla writes from prison, engaged to her college friend Rupert, asking Lily's forgiveness. Carla's biological father, the anonymous buyer of The Italian Girl, has come forward to care for Poppy. Lily acknowledges that Carla's sentence may not be fully just but cannot risk revealing the truth. She never took a DNA test for Tom, preferring to live with the uncertainty, and resolves to move forward, accepting that everyone carries layers of truth and deceit.