The novel opens in 1968 aboard a private jet. Emma Harte, a seventy-eight-year-old business tycoon, flies from Texas to New York with her granddaughter and protégée, Paula McGill Amory, after ousting the president of the Sitex Oil Corporation. Emma controls a sprawling empire: the Harte department store chain, Harte Enterprises, a 40% stake in Sitex Oil, and vast holdings in Australia. At her New York offices, her secretary, Gaye Sloane, confesses that she overheard two of Emma's sons, Robin Ainsley and Kit Lowther, plotting to force Emma into retirement by threatening to prove her senile, then selling off her companies. Emma is devastated but steels herself, recognizing her children have made a fatal mistake: They underestimated her. She books flights to London, resolving to outmaneuver them.
The narrative shifts to 1904 and Emma's origins as a fourteen-year-old kitchen maid in Fairley village, Yorkshire. Her mother, Elizabeth Harte, is dying of consumption (tuberculosis), and her father, Big Jack Harte, is a former soldier broken by grief. Each morning Emma walks across the dark moors to Fairley Hall, where she scrubs floors and tends fires for the wealthy Fairley family. On one such journey she meets Blackie O'Neill, a charismatic eighteen-year-old Irish construction laborer whose vivid descriptions of Leeds ignite her imagination and her determination to escape.
At Fairley Hall, Emma endures the cruelty of Murgatroyd, the butler. The Squire, Adam Fairley, is a cultured man trapped in a loveless marriage to Adele, who has a mental health condition that manifests in delusions and confusion. Adam's elder son, Gerald, is greedy and devoted to the family's wool business; his younger son, Edwin, is gentle and drawn to the law. When Adam's sister-in-law, Olivia Wainright, arrives for an extended visit, she improves Emma's working conditions and recognizes the girl's exceptional intelligence. Emma begins developing her organizational abilities and a secret ambition she calls her "Plan with a capital P."
Elizabeth Harte dies, and Emma renounces her belief in God, reasoning that no merciful deity would permit such suffering. Over the following years, she and Edwin develop a close friendship during his school holidays. They discover a hidden cave on the moors, and during a thunderstorm they shelter there. Physical closeness leads to their first sexual encounter, and Edwin declares his love.
When Emma discovers she is pregnant, Edwin suggests she terminate the pregnancy, then falls silent about marriage, paralyzed by fear of his father and the class divide between them. Emma tells him she will leave Fairley forever. Walking away through the rose garden, she is consumed by a hatred that crystallizes into iron ambition: She vows to become so rich and powerful that she will never be vulnerable again and swears revenge on the Fairleys.
Emma flees to Leeds, where she finds lodging with Mrs. Daniel and presents herself as "Mrs. Harte," claiming a husband in the Royal Navy. She rescues Abraham Kallinski, a Jewish immigrant tailor, from an anti-Semitic attack. The Kallinski family befriends and employs Emma, becoming her surrogate family. Abraham's elder son, David, recognizes a kindred spirit in her. Blackie returns from Ireland and proposes marriage when he learns of her pregnancy, but Emma refuses. He insists on being named as the father on the birth certificate to spare the child stigma.
Emma moves to Armley to share a house with Laura Spencer, Blackie's gentle friend, and works at a local mill while sewing and baking for sale in every spare hour. Her daughter, whom she accidentally names Edwina after Edwin, is born in March 1906 and placed with a cousin in Ripon so Emma can work. Emma's rise is relentless: She opens a shop, expands to three storefronts, and builds a reputation for quality goods. When Gerald Fairley tracks her down and attempts to assault her, Emma fights him off but recognizes she needs the protection of a husband. She marries Joe Lowther, a decent landlord who loves her, though she herself loves David Kallinski. A son, Kit, is born in 1911. Emma acquires a wholesale warehouse, purchases a failing department store in Leeds, and transforms it into the flagship Harte's.
She also secretly creates the Emeremm Company, a holding and acquisition firm through which she begins dismantling the Fairley business interests. Shortly after Emma's departure from Fairley, a fire erupts at the Fairley mill, and Big Jack dies saving Edwin's life, a sacrifice that deepens Emma's hatred immeasurably.
During the First World War, Joe and Blackie enlist. Joe is killed at the Somme. Laura, pregnant after years of miscarriages, refuses a cesarean section because it would endanger her baby. She dies giving birth to a son, Bryan, and Emma raises him alongside her own children.
In 1918, Emma meets Paul McGill, a magnetic Australian officer. Paul is married but estranged from his wife, Constance, who has an alcohol addiction; he also has a son, Howard, who has an intellectual disability. Emma and Paul become lovers, beginning the defining relationship of Emma's life. When Paul returns to Australia, his secretary, Marion Reese, intercepts and destroys all their correspondence. Believing Paul has abandoned her, Emma marries Arthur Ainsley, a handsome but shallow and unfaithful man. Twins Robin and Elizabeth are born in 1921. Meanwhile, teenage Edwina obtains her birth certificate, discovers her illegitimacy, and confronts Emma before severing all contact, a rift that becomes one of Emma's deepest sorrows.
Emma's brother Frank arranges a reunion with Paul in 1923. Paul explains Marion Reese's treachery, producing a written confession, and they resume their relationship. Their daughter Daisy is born in 1925. Through the Emeremm Company, Emma forecloses on Gerald Fairley's mills, purchases Fairley Hall, confronts Gerald in his own home, and orders Blackie to demolish the estate brick by brick. She turns the grounds into a park named after her mother. She then founds rival newspapers that erode circulation of the Fairley-owned
Yorkshire Morning Gazette until its board ousts Edwin, completing her revenge.
In 1939, Paul suffers a catastrophic car accident in Sydney that leaves him paralyzed and disfigured. Unable to accept life with his injuries, he takes his own life. A letter arrives days later in which he begs Emma's forgiveness and tells her Daisy is her future. Paul's will leaves Emma his entire fortune, making her one of the richest women in the world. Emma endures the Second World War, managing her businesses while her sons and sons-in-law serve in the military, and emerges with her empire and family intact.
The narrative returns to 1968. After a bout of pneumonia, Emma gathers her family at Pennistone Royal, her Yorkshire country estate, for what she describes as a post-illness reunion. She privately tells Edwina that her real father was Edwin Fairley, not Blackie. She meets Jim Fairley, Edwin's grandson, who delivers a painted pebble Edwin kept until death, along with his deathbed message begging forgiveness and urging the two families to unite. Emma forgives Edwin and blesses Paula and Jim's engagement.
That evening, Emma reads her will aloud. She disinherits her four scheming children entirely, distributing her empire among her grandchildren: Elizabeth's son, Alexander Barkstone, receives controlling shares of Harte Enterprises; Paula inherits the department store chain; and the McGill estate passes to Daisy and then to her children, Paula and her brother Philip. Emma offers each disinherited child one million pounds in exchange for signing contracts agreeing never to contest the will. All four sign. Afterward, sitting alone with Blackie, Emma reflects on her extraordinary life. When Blackie asks if she discovered any special secret along the way, Emma smiles: "It is to endure."