Belfield (the Robinsons’ neo-Gothic house just outside London) hosts a reunion of the five Saratoga friends for the first time since Virginia’s wedding. Mabel arrives from America with infant Rosabel, Lizzy presides, and Virginia and Conchita are radiant. Only Nan remains childless, haunted by her miscarriage and her refusal to (as her husband maintains) “cooperate in producing a new [heir]” (329). At tea, Lizzy lists arriving guests and notes that Guy Thwarte has suddenly declined. Conchita calls him a widower resistant to remarriage, and Lizzy teasingly hints that he avoided Belfield because of Nan. Nan understands that Guy loves her and is staying away to protect them both. She resolves that no one must ever know and dreams of Proserpine, reading her own fate into the myth but reminding herself that she lives in “the unmythological world” (332) of railways, gaslight, and Queen Victoria.

Nan’s presence opens doors; the entire party is invited to Bainton, a neighboring house favored by the Prince of Wales. On the terrace, the Prince arrives upon the arm of Lady Churt. In a deliberate slight, Lady Churt announces that the Duchess of Tintagel extracted 800 pounds from the “wretched Duke” (334) in order to hush blackmail arising from Guy Thwarte’s supposed visit to her bedroom on Christmas Eve. Hearing this, Nan blanches, and Virginia, Lizzy, Mabel, and Conchita close ranks around her, forcing Lady Churt into a barbed apology. In the aftermath of this scandal, Conchita whispers to Nan that only Miles Dawnly knew of the money, hinting at the rumor’s path. That night, Hector worries about the scandal, but Lizzy’s calculation is bolder. She reasons that if Nan loves Guy and separates from the Duke, the Duke will need a divorce in order to remarry and secure an heir; Mabel, newly widowed and very wealthy, would be the ideal next Duchess. Hector admires his wife’s strategy, and with proprietary firmness, he also admires his wife’s plans for him to “maneuver for a peerage” (336).

After the public slight at Bainton, Nan spends a sleepless night and steels herself for breakfast, where Sir Blasker announces that Guy Thwarte has withdrawn his candidacy for Lowdon. Lizzy notes that Nan seems genuinely surprised. A summons from Folyat House soon arrives. In the Duke’s London study, Ushant demands Nan’s immediate return and obedience. Nan calmly admits that she loves another man, affirms that there has been no misconduct, and declares her wish to leave Ushant because their life together has become intolerable. In response, Ushant refuses attempts to confine her and orders the household to prevent her departure. Nan slips out through the service passages with the help of a young footman, escapes into the London streets, and makes her way to Miss Jacky March’s house, where Miss Testvalley swiftly removes her to Hyde Park and advises a discreet refuge with the Testavaglia family in Denmark Hill. Nan has ample funds, thanks to a recent remittance from her father.

Before hiding, she returns to Belfield by cab and shocks her friends by announcing that she has left the Duke. Virginia furiously accuses her of endangering them all. Conchita remains affectionate while Mabel is alert and noncommittal. Lizzy offers practical help and quietly reassigns Nan’s maid, Mabbit, to Mabel.

In private, Lizzy probes Nan’s resolve. Nan insists that she cannot and that Ushant needs a different wife. She even suggests that Mabel would suit the role. Later, Lizzy and Hector coldly game out futures in which a Tintagel remarriage, a Thwarte inheritance, and a county reconciliation might realign all parties. Departing quietly for London, Nan asks Lizzy to keep her destination secret, then travels by train to Denmark Hill and the shelter of Miss Testvalley’s family.

The Duke learns that Nan escaped Folyat House and recognizes that he cannot employ physical force to compel her to return. He then chooses to interpret her avowal of loving another man as a form of “theft” from his own marital rights. He imagines society as a clockwork mechanism that Nan has disrupted and admits that he wanted a tractable bride rather than a full partner. At his Tory club, he learns that Guy Thwarte has withdrawn from the Lowdon by-election and promptly consults solicitor Cyril Dinsmore. Dinsmore outlines legal paths of separation or divorce, citing Nan’s desertion and refusal to “perpetuate the ducal line” (353). The Duke insists on a quiet, unsensational resolution and asks for a plan before the Longlands Assizes.

In London, Miss March, thrilled and alarmed by Nan’s flight, secretly writes to Miss Testvalley. She proposes two respectable maid candidates for Nan, stressing that her name must not be used. Miss Testvalley returns the Glenloe girls to Champions and finds that Lady Glenloe has been summoned to Allfriars by Lord Brightlingsea’s grave illness. She delicately informs Miss March, acknowledges the anonymous help, and learns that Sir Helmsley Thwarte has suffered another fall. Miss Testvalley refuses to gossip, reflects on Sir Helmsley’s culture and temper and on her own wary hopes about his proposal. Anticipating the imminent end of her current position, she presents Kitty and Cora with a long reading list.

Guy Thwarte prepares to pursue engineering work in Greece and India, and he uses relentless meetings and language lessons to quiet his thoughts of Nan. Before departing, he resolves to see her once in order to apologize for his outburst at Champions and to say farewell. His servant cannot deliver a note to Belfield or Folyat House, so Guy visits Conchita, who recounts Lady Churt’s public slander at Bainton and clarifies that Nan lent money to her, not to him. Conchita also reports that Nan has left the Duke and vanished from Belfield. Shaken yet hopeful, Guy consults his solicitor and school friend, Anthony Grant-Johnston. Anthony warns that the Duke may pursue divorce and that detectives and publicity are likely. He cites his sister’s ruin by false testimony and recalls how Lady Churt forbade him from bringing his divorced sister to the house at Runnymede. Still bristling from this injustice, he is more than willing to help Guy. He advises Guy to avoid being seen with Nan, but Guy insists on finding her.

Guy seeks Hector Robinson at the House of Commons, and under the pretext of family business, he asks for Nan’s whereabouts. Following Lizzy Robinson’s quiet strategy, Hector directs him to Miss Testvalley in Denmark Hill without naming Lizzy as the source. That night, Hector and Lizzy assess the spreading gossip and Nan’s likely innocence. Lizzy states that if Nan truly separates from Ushant, they can position Mabel Whittaker as an ideal future Duchess. Through Miss March’s matchmaking and Virginia’s access at Allfriars, where Lord Brightlingsea lies gravely ill, Mabel could be introduced to the Dowager and to the Duke. A gift of Paul Revere silver will ease the approach, while Virginia publicly “disowns” her sister to reassure the Folyat circle.

Nan uses her maiden name in Denmark Hill, hiding with Miss Testvalley’s family. Only Lizzy and Miss Testvalley know her whereabouts. The Testavaglia household is modest but intellectually rich, featuring shelves of books, portraits of Italian patriots, and simple meals. Old Gennaro speaks to Nan about emancipation, Stowe, and Italian unification, urging her to value a nobility of spirit above rank. In the kitchen, Serafina and her homesick cousin Anna describe immigrant lives, prompting Nan to imagine work as a cashier or teacher rather than remaining dependent on her father. Resolved to leave England to avoid harming Guy’s prospects, Nan drafts a letter to Laura, declining the suggestion of hiring a maid and asking for guidance toward paid work, perhaps in a settlement house or orphanage with room and board. She longs to see Guy once for a proper farewell but doubts her own heroism.

Nan arranges a discreet meeting with Virginia at St. Paul’s. Amid organ music, Virginia accuses her sister of creating a scandal and warns that the Duke may divorce her. Nan insists that there is no misconduct with Guy and asks Virginia to write a strong reference for Miss Testvalley, whose livelihood may suffer through her association with Nan. Virginia gives no promises and coolly warns that their mother would be enraged if Nan were to return to New York. On the omnibus home, Nan rejects the role of ingenue. She reflects that she is 23, married, bereaved of a child, likely to be divorced, and in love with a man she cannot marry. She resolves to write to the Duke and to her father, to plan useful work in America, and to seek one final, dignified meeting with Guy.

Guided by Hector Robinson’s tip, Guy finds Nan with the Testavaglia family. Serafina lets him into the house. Nan, resolved to offer a formal farewell, meets him at the door, where they kiss for the first time, confessing their love. Guy reveals that he has abandoned the Lowdon candidacy and intends to leave England within a fortnight to survey a Greek railway; he asks her to come. Nan refuses to imperil Honourslove or his future, then discloses that she left the Duke after he threatened to enforce his marital rights; she escaped through the mews and expects a divorce for desertion. Both she and Guy fear that Lady Churt’s lie may push the Duke toward an adultery suit in which Guy is named. Guy insists that he will protect Nan, even proposing that they leave together chastely, but Nan asks to consult Miss Testvalley before deciding. He accepts this and departs at once to settle his own legal and familial matters.

Guy’s solicitor outlines the era’s uneven divorce law: husbands, especially noble ones, can hire spies, sway servants, and often secure decrees. Although courts abhor “collusion, condonation, or connivance” (387), they sometimes show latitude to peers. He advises Guy and Nan to maintain meticulously secret travel arrangements if Nan agrees to flee, and Guy agrees. At Honourslove, Sir Helmsley erupts with anger, declaring that Guy has betrayed centuries of duty, abandoned Parliament, and invited a ruinous scandal. Guy maintains that there has been no misconduct, that Nan left the Duke for her own reasons, and that he hopes to marry her once she is free. His father rails against American women who marry British aristocrats, labeling them “pirates” (389). He demands to know Nan’s hiding place and vows to sell the Holbein.

Miss Testvalley arrives early at Denmark Hill, already rebuking herself for having helped Nan to fall in love with Britain’s “Celtic gloaming” (390). By breakfast, she learns that Lizzy proved unexpectedly sympathetic, that Hector let slip Nan’s hiding place, and that Nan will not return to Ushant. Guy appears and explains that he has taken an engineering post that will carry him to Greece and India. He asks Nan to come now and marry him when she is free. He promises to guard her honor as fiercely as his own. Nan believes that to live with Guy before the decree would not be immoral, but to return to Ushant to “produce sons” (395) would be. She will write the Duke that she is going away and hopes to be with someone else, an admission meant to hasten a quiet suit. Miss Testvalley tells them to expect detectives and bribed servants and to know that they will be cut off from English society for years, perhaps forever.

A plan takes shape. Nan will cross to Boulogne and stay at the Hôtel de Boulogne et de l’Univers. Guy will follow, and from there, they will slip south by sea toward the Piraeus. To avoid scandal at the ports, Nan will travel with Serafina’s niece, Anna, as an Italian “daughter” rather than a compromised friend. Privately, Nan imagines herself as an Italian and comes to see Miss Testvalley as her “mother” (398).

Conchita meets Nan at St Paul’s Cathedral. Nan states her plan to go to Greece with Guy Thwarte. Conchita approves, noting that a divorce for adultery will proceed “a thousand times faster” (399) than one for desertion, allowing both Nan and the Duke to remarry sooner. She agrees to help Miss Testvalley secure a new post and to attest that the governess did not influence Nan’s decision. They exchange addresses and promise to write.

That evening, Miss Testvalley writes to Sir Helmsley to end their engagement. She states that, while she regrets the consequences, her regard for his son and for Nan requires her not to stand in the way of their future. She seals and sends the letter, expecting anger or silence in response.

At Belfield, Hector Robinson questions the feasibility of Lizzy’s plan to place Mabel as the Duke of Tintagel’s future wife. Mabel says she will not marry for money. Lizzy outlines a practical approach based on the Naxos throne: Mabel holds one fragment of the artwork, while the Duke holds the other. Mabel will request permission to view the Longlands fragment, which should lead to contact, an invitation, and continued acquaintanceship since “the Duke loathes having a fragment” (403). The intention is to offer to restore her fragment to Longlands as a donation, not a sale.

At Honourslove, Sir Helmsley receives Miss Testvalley’s letter and a new request from Rossetti for funds. He reacts with anger toward those he considers responsible for the disruption of his plans, including his son’s departure and the collapse of his hopes.

Nan and Guy agree to meet in Boulogne, then continue toward Greece. Nan asks him to bring a side-saddle for the donkey that she will ride in Greece. At Charing Cross, Nan departs on the boat train with Anna, Serafina’s niece, as her companion. Miss Testvalley sees her onto the train, remains on the platform until it leaves, and takes a cab home with the demeanor of a “a female warrior raising a sword to lead the remnants of an army to battle” (406).