In Naples, Italy, Tierney Callaghan attends the baptism of her infant nephew, Gennaro, or “Nero.” Nero is the son of Tierney’s brother, Tiernan, and his wife, Lila Ferrante (Achilles’s sister and Vello’s daughter). Tiernan and Tierney are members of an Irish crime family that is now uneasily allied with the Ferrantes via Tiernan and Lila’s marriage. Tierney is irritated by the presence of her longtime adversary, Achilles Ferrante, and they exchange hostile words. Achilles surveils Tierney at all times, and she cannot go anywhere without his men accompanying her. He also has the right to choose her husband, which infuriates Tierney, who is determined to maintain her independence. Vello and Tyrone Callaghan (the father of Tiernan and Tierney) attend the baptism. (The ceremony takes place prior to the events depicted in the Afterword.)

The baptism involves a gruesome ritual: Achilles murders a member of a rival crime family, and Gennaro is christened with the man’s blood. This ritual is a traditional part of initiating Ferrante sons into the family. The service is violently interrupted when armed men storm the church, detonating smoke flares and opening fire. Amid the chaos, Achilles shields Tierney by pushing her under a pew and giving her a pistol. Tierney tries to protect her brother and his family and then attempts to flee before a bomb detonates. Achilles protects her again and alludes to a shared romantic history and ongoing sexual tension.

The narrative flashes back to when Tierney and Achilles first met. Tierney was 14; she and Tiernan had recently escaped a Siberian prison camp and were living in New York with their father and elder brother, Fintan. Traumatized and speaking little English, Tierney was withdrawn and isolated. One night, after she has a nightmare about the abuse she suffered, a teenage boy enters her room. The chapter does not explain why Achilles is in the house. He quietly covers her with her duvet. When she cautiously touches his cheek, he flinches before leaning into her hand, seemingly starved for affection. He stays in her room, watching over her until morning, providing a silent, protective presence.

One week after the baptism, Achilles is interrupted in his New York apartment. He has just finished killing a man who recently had sex with Tierney. Achilles refers to Tierney as “my woman” and reflects that he has murdered all of Tierney’s previous sexual partners; his constant surveillance also makes it hard for her to have sexual encounters in the first place. His brothers Luca and Enzo arrive at his apartment and summon him to an emergency meeting with their father. Achilles reflects that although Luca is the eldest, he, Achilles, is most likely to be named Vello’s successor, since neither of the other two are suitable. 

Luca explains context for the meeting: The man killed at the baptism was a member of the Coppola crime family. The bombing of the church was a retaliation for this act, and now Stefano “Sangue Blu” Coppola has come to negotiate a deal with the Ferrante family. He is heading for their family estate on Long Island. Achilles reluctantly agrees to join them for the meeting. His brothers express their misgivings that he keeps killing men who sleep with Tierney, but Achilles feels justified.

The Ferrante family meets with Stefano Coppola to negotiate peace. Coppola agrees to a truce and proposes a business alliance but makes a shocking final demand: He wants to marry Tierney Callaghan. Achilles immediately objects. The Ferrante family and Tierney’s brother, Tiernan, hold a private intervention with Achilles, revealing that Tiernan has already approved the marriage. Vello then presents Achilles with an ultimatum: If he permits the marriage, he will be named the new head of the family. Seduced by the prospect of power, Achilles agrees to the deal. 

To further test him, Vello orders Achilles to personally deliver Tierney to Coppola in Naples. Achilles agrees and the Ferrante men promise Coppola that Tierney will be brought to him by the end of the month.

The narrative flashes back to the night Tiernan and Tierney escape from the Siberian prison camp as teenagers (prior to Tierney meeting Achilles). Alex “Lyosha” Rasputin is the teenaged son of the man who holds the twins captive, but he has forged a close friendship with them anyways. Tierney reflects on her complicated attraction toward Alex and her regret that he is unaware of their plans to escape. As Tierney and Alex prepare to tattoo each other with matching tattoos, Tierney expresses to feelings of being overwhelmed. She asks Alex to kiss her, but he gently refuses, not wanting to take advantage of her vulnerability, and instead kisses her forehead.

Achilles arrives unannounced at Tierney’s apartment and announces that he has found her a husband. Tierney is stunned because she had been confident that Achilles would never tolerate her marrying another man. He orders her to pack, telling her he will be delivering her to her new husband shortly. After he leaves, Tierney collapses to the floor in devastation.

Shaken after the conversation, Achilles goes to the family-owned nightclub, the Forbidden Fruit, where he finds his brother, Enzo (Achilles suspects that Enzo is secretly gay). Achilles begins drinking heavily and consuming drugs, alarming Enzo.

Tiernan forces Tierney onto a private plane bound for Italy, where she will marry Coppola. She is joined on board by Achilles and various men who work for the Ferrantes. At first Achilles ignores her, but Tierney tries to provoke him. She pleads with him to call off the marriage and tries to persuade him that Vello will still name him successor, even if he reneges on the plan. Eventually, Achilles proposes a deal: Tierney will be his for a weekend. In exchange, he will return her to New York and deal with the fallout of calling off the arranged marriage. Additionally, after the weekend, Tierney will move away and never see him again. She readily agrees, desperate to avoid marriage. 

Hours later, still aboard the plane, Achilles summons Tierney to the lavatory. He engages in rough, demeaning sex with her and afterward forces her to sit on his lap in front of his men, establishing his dominance for the weekend ahead.

Upon arriving in Naples, Tierney and Achilles are met by two of Coppola’s men who are there to collect her. Achilles kills them both. While his men clean up the crime scene, he and Tierney depart on a motorcycle. He stops at a secluded cliff overlooking the city and questions her about their shared past. Tierney lies and claims she never cared for him and does not regret hurting him. He retaliates with another rough sexual encounter, focusing solely on his own pleasure. 

Afterward, hurt and humiliated, Tierney lashes out and tries to flee. Achilles seems confused and explains that he thought Tierney only enjoyed rough and degrading sexual encounters. She clarifies that while she does enjoy consensual rough play, she wants to be a willing partner and wants her pleasure to be an important factor in their encounter. She lays out ground rules that Achilles willingly agrees to: “[S]top being mean to me. Stop mentioning our past. And stop denying me orgasms” (108). She also institutes a safe word, “Ford Prefect,” which is an unspecified reference to their shared past. Achilles agrees to the conditions and admits that he simply wants to stop being so preoccupied with her.

Tierney and Achilles check into a seaside hotel in Naples. He brings her to orgasm twice, refusing to engage in any rough or humiliating acts even though she requests them. Tierney is secretly astonished that she can climax without any rough sex. She is also shocked when she realizes that Achilles did not orgasm during either encounter and focused on her pleasure instead.

As the weekend progresses, Achilles and Tierney have frequent sexual encounters. In between, she goes on lavish shopping sprees while he dismantles Stefano’s gang operations and seizes new territory in Naples for the Ferrante family to control. As word spreads that he has broken the deal with Coppola, Achilles ignores frantic calls from his father and brothers. During a sexual encounter, he resolves that before their time ends, he wants to make Tierney feel regret for what their relationship could have been, acknowledging that he desires her heart and soul, not just her body.

On their last night in Naples, Achilles takes Tierney on a romantic dinner date. Unsettled by his uncharacteristic kindness, she confronts him about stalking her. Achilles reveals the full extent of his surveillance, admitting he installed a camera in her apartment and a tracker on her phone, which he uses to ensure her safety and check that she isn’t having nightmares. He also confesses he wanted to punish her by forcing her into a miserable marriage. Tierney has a moment of emotional vulnerability, admitting to herself that she left Achilles years ago because she loved him too much and believed she was too broken for him. 

Back at the hotel, while they are having sex, Tierney spontaneously attempts to kiss him (violating one of the boundaries he established). Achilles freezes and uses the safe word.

Achilles refuses to kiss Tierney. They proceed with having sex, but Tierney is upset afterward. When Achilles confronts her, she accuses him of being unable to forgive her for their past. She also admits that she has not forgiven herself either. This confession prompts Achilles to kiss her passionately. They have sex again, this time kissing throughout. Afterward, as they lie in bed, Achilles tells Tierney that he forgives her.