Archibald Martin Floyd, the wealthy senior partner of the London banking house Floyd, Floyd, and Floyd, shocks his Kentish neighbors when, at forty-seven, he marries Eliza Percival, a penniless actress he discovers in a Lancashire theatre. Eliza is the daughter of a merchant captain named Prodder and had a brother who quarreled with their father and ran away to sea, never to be heard from again. The marriage is happy, but about a year after the birth of their daughter Aurora, Eliza dies suddenly.
Archibald raises Aurora with unchecked indulgence. She grows into a beautiful but willful young woman who loves horses, dogs, and racing. Her cousin Lucy Floyd, a gentle girl from Alexander Floyd's family, serves as her confidante. When Aurora is seventeen, a crisis erupts: after long rides with a handsome young groom, she quarrels with her father, and the groom is dismissed. Three days later, Archibald places Aurora in a Parisian finishing school. She returns fourteen months later, pale and haggard. In a charged exchange, Archibald asks whether the man involved in her secret scandal is dead. Aurora confirms that he is.
At Aurora's nineteenth birthday ball, two suitors appear. Captain Talbot Bulstrode, an officer in the cavalry regiment the 11th Hussars, is a proud Cornishman who demands absolute moral purity in any potential wife. John Mellish, a hearty Yorkshire landowner, falls openly in love with her. Over the following weeks at Brighton, Talbot visits daily, drawn to Aurora while Lucy silently loves him. Spurred by jealousy of John, Talbot proposes one November evening, but Aurora rejects him without explanation. John also proposes and is refused.
Two days later, Talbot finds Aurora in a faint, a sporting newspaper at her feet reporting a jockey named Conyers killed in a steeplechase. He proposes again, and Aurora accepts. At Christmas, however, Talbot receives a letter from his mother revealing that Aurora ran away from her Paris school within a fortnight of arriving. Aurora admits this is true but refuses to explain where she spent the missing year. Talbot breaks the engagement, and Aurora collapses into a severe fever lasting months.
John remains devoted throughout Aurora's illness. During a convalescent tour in Normandy the following September, he proposes again. Aurora reveals that Talbot rejected her because of a secret she cannot share. John declares he would have trusted her regardless, and Aurora accepts. They marry in late November and settle at Mellish Park, John's Yorkshire estate. She acquires two enemies: Mrs. Walter Powell, an envious widow serving as housekeeper, and Steeve Hargraves, a stable helper with an intellectual disability whom the household calls the "Softy." Aurora horsewhips Steeve for kicking her dog, and John dismisses him. Steeve departs muttering threats.
At the York Spring Meeting, the group encounters Talbot. During a visit to Mellish Park, Talbot recognizes Lucy's love and proposes; they marry in June. John Pastern, a respected authority in the racing world whose recommendation John regards as all-sufficient, later suggests a trainer named James Conyers for John's stables. When John reads the letter aloud, Aurora collapses at the name. She insists Conyers must come; John agrees, choosing to trust her despite his alarm. The trainer arrives in early July and installs himself at the isolated north lodge, defying John's ban by hiring Steeve as his servant.
One evening, Aurora slips out to meet Conyers at the lodge. Mrs. Powell follows and eavesdrops. Aurora offers Conyers two thousand pounds to emigrate to Australia and leave her in peace; their exchange reveals deep mutual hatred. She obtains the money from her father in London; Archibald carefully records the number of every note. Meanwhile, Captain Samuel Prodder, Eliza's long-lost brother, arrives in England after decades at sea. Having learned of his sister's death, he travels to Mellish Park to meet his niece.
On the evening of the murder, Aurora meets Conyers in the wood for their final transaction. Prodder, hiding nearby, witnesses Aurora's declarations of hatred. Minutes later, a pistol shot rings out. Prodder and a young driver find Conyers dead by a pool, shot in the back. Prodder carries the news to the house and flees, terrified that his testimony would incriminate his niece.
The inquest returns a verdict of murder by persons unknown, but afterward the constable produces a blood-stained document found sewn into Conyers's waistcoat: a marriage certificate from Dover, dated July 2, 1856, recording the marriage of James Conyers to Aurora Floyd. John learns his wife secretly married her father's groom at seventeen, making her marriage to John bigamous. He walks out onto Harper's Common and lies in the grass for hours before forgiving her.
Steeve visits Aurora and reveals that the certificate has been found. Convinced she has lost John's love, Aurora flees to Talbot and Lucy in London and tells Talbot the full story. She ran away from school to marry Conyers, discovered his infidelity, left him, and lied to her father that Conyers was dead. When she believed a false newspaper report of his death, she married John, only for Conyers to reappear as John's trainer. She paid him two thousand pounds to emigrate on the night he was killed.
Talbot advises Aurora to remarry John legally. John arrives in London searching for Aurora, and they reunite, obtain a new license, and quietly remarry at a small City church. Back at Mellish Park, the shadow of murder lingers. Before her dismissal, Mrs. Powell had sent anonymous letters to the authorities implicating Aurora. John discovers the murder weapon, his own pistol found near the pond, and realizes it was taken from his gun room, where Aurora had been on the morning of the killing. Combined with her presence in the wood, this drives John to suspect Aurora. He withdraws, and Aurora sinks into despair.
Talbot and Lucy arrive at Mellish Park. Talbot confronts John, who admits his suspicion but insists his love has never lessened. Talbot insists Aurora is innocent and that they must find the real killer. A Scotland Yard detective, Joseph Grimstone, is already investigating. Aurora, shocked to learn she has been suspected, reveals Steeve was in the gun room that morning, establishing his chance to steal the pistol. Grimstone traces a blood-stained brass button found near the body to a waistcoat given to Steeve, but the Softy slips away and disappears.
Talbot discovers the murderer when, riding home late at night, he sees a light in the empty north lodge. He confronts Steeve, who has returned to retrieve the incriminating waistcoat and a pocket-book containing Aurora's two thousand pounds, hidden in the wall. They fight; Steeve nearly kills Talbot with a knife before Captain Prodder, prowling nearby, crashes through a window and saves his life. They subdue Steeve and recover the money and the waistcoat with one brass button missing.
Stephen Hargraves is tried at York, convicted, and executed. He confesses that he followed Conyers, shot him in the back while the trainer counted the bank-notes, and used a waistcoat button as wadding. John and Aurora leave Mellish Park for the south of France with Archibald. Talbot and Lucy join them at Nice, and Aurora gives birth to a dark-eyed son who resembles her dead mother. Captain Prodder is welcomed into the family. The novel closes with Aurora bending over her firstborn's cradle, her turbulent past yielding at last to domestic peace.