Kate Blackwell, matriarch of the Blackwell family and head of her father's multinational business empire, Kruger-Brent Ltd., celebrates her ninetieth birthday with her family and friends, but is more focused on the ghosts of her past who are there. She recalls how the company started, and the story is told through flashback through different members of Kate's family.
A hundred years ago, Kate's father Jamie McGregor leaves Scotland for Klipdrift, South Africa to find wealth by mining diamonds. He makes a contract with a local Dutch merchant, Salomon Van Der Merwe, but is double-crossed after nearly dying to find an untapped diamond mine only to find out that the contract gives Van Der Merwe the entire mine while Jamie is paid minimum wage for his services. Jamie tries to protest, but he is beaten and left for dead in the desert. He is saved by Van Der Merwe's servant, Banda, who wants revenge on Van Der Merwe for raping his sister, who died giving birth to Van Der Merwe's child. They manage to pull off a dangerous heist and take millions worth of diamonds, and Jamie returns to Klipdrift under the persona Ian Travis, a widowed millionaire looking for business opportunities. He catches Van Der Merwe's attention and convinces him to let his daughter, Margaret, tour him around Klipdrift, and Jamie seduces her and impregnates her. When Margaret announces her pregnancy, Jamie reveals his true identity and refuses to marry her, shaming her conservative father. Margaret is kicked out, eventually giving birth to Jamie Jr. Meanwhile, Van Der Merwe becomes a social outcast and heavily borrows from the local bank, not knowing that Jamie owns it. Jamie tricks Van Der Merwe to borrow heavily, and then calls in all his debts when he knows Van Der Merwe cannot afford to pay. Jamie later finds out that Van Der Merwe committed suicide, but feels an empty victory.
Jamie's company Kruger-Brent Ltd., thrives in South Africa. He hires David Blackwell for his ambition and determination which mirrors Jamie's own. In an attempt to make Jamie love her, Margaret abandons her son with him, and Jamie slowly loves his son. Margaret twists Jamie's arm to marry her, threatening him with leaving for America with their son, and while her reputation is restored, Jamie acts cold towards her and openly keeps a prostitute named Margaret as a mistress. After a drunken fight with the mistress Margaret, Jamie mistakenly apologizes to his wife Margaret and has sex with her, resulting in their second child, Kate. Banda warns Jamie that the Bantu rebellion may harm his family and steals one-year-old Kate from her crib during a riot in order to protect her. However, he did not reach Jamie Jr. in time, and he was left to die in the desert. The news of this causes Jamie to have a stroke, and dies after five months of paralysis; Margaret runs Kruger-Brent with Blackwell's aid. During the rebellion, Margaret and Kate are taken as prisoners-of-war due to being South African citizens, and Kate realizes the need for power so she will never feel helpless.
Kate grows up falling in love with Blackwell, despite their large age difference and his view of her as nothing more than a child, and vows that she will marry him one day. After her mother's death, she decides to get serious about running the company and goes to business school. Upon her return, she learns that Blackwell is engaged and is planning to leave Kruger-Brent for his fiance's family business, and secretly buys out his fiance's company, knowing that David hates sell-outs. She seduces him and they marry after two months.
At the beginning of World War I, Kate capitalizes on the war by planning to sell bullets and weapons, but is stopped by Blackwell, who is against it. He begins to realize Kate's obsession with the company, and enlists for the war and is gone for four years. Kate decides to push through with her idea when she sees the opportunity being wasted, and when David arrives, he is annoyed by Kate's actions. Kate becomes pregnant, and she realizes her own obsession when she is happier about good news about the company than a married life with David and their upcoming son. Two months before the baby's birth, David is killed in a mine explosion and Kate gives birth to Anthony "Tony" Blackwell.
With no one to stop her, Kate pours all her attention to Kruger-Brent and makes it a global success. She is a demanding mother to her son, expecting nothing but the best from him, but is disappointed to see that he stutters in her presence and would rather go into art than business. After World War II, Tony goes to art school in France and begins dating Dominique, a French model. During an exhibit, Kate pays-off a renowned French critic to bash Tony's work, despite his honest opinion that Tony could have been successful, in order to end Tony's career and push him to take over the business. Tony eventually finds out that Dominique is a model from one of Kruger-Brent's agencies and has been spying on him for his mother, and Tony gains the courage to stand up against her and leave.
Kate manipulates Tony into marrying Marianne Hoffman, as she wants both Marianne's father's patents and a grandchild who can take over the company since Tony will not. She pushes Marianne to carry out her pregnancy despite warnings from her doctor that her health makes it unsafe to bear children, and Marianne dies giving birth to twin daughters. Tony learns of Marianne's health issues and how his mother persuaded her to carry out the pregnancy and, after bumping into Dominique and her boyfriend, that his mother was responsible for the end of his career, Tony goes insane and tries to kill Kate, but misses. He is lobotomized and sent to an asylum, while Kate takes care of both the company and her granddaughters, Eve and Alexandra.
Eve, the older twin, is manipulative and evil, and despises Alexandra, whom she sees as an interloper, and tries to kill her several times. Kate decides to name Eve heir to Kruger-Brent for her Kate-like personality while Alexandra, clumsy but kind-hearted, will receive the charity foundations and will live a comfortably wealthy life. Kate eventually finds out about Eve's evil nature and disinherits her, quietly but obviously turning to Alexandra as her heir. Eve meets George Mellis during a party, and after getting raped by him, she digs into his past and finds out that they share similar backgrounds, and they plot to have Alexandra marry Mellis and then kill her, leaving George the heir of Kruger-Brent. Eve helps Mellis win Alexandra's love and Kate's approval, and they marry.
One night, Eve taunts Mellis to the point that he assaults her. She recovers without any scars due to the work of talented surgeon Keith Webster. Kate reconciles with Eve after hearing about her, and restores Eve to her will. Eve realizes that Alexandra's death will put her under her grandmother's suspicion and begs Mellis not to continue. However, Mellis wants to inherit Alexandra's share and goes on with a honeymoon ploy in a private yacht, where he intends to push Alexandra overboard and kill her. Eve hastily stops the plan by delaying Alexandra and posing as her sister to kill Mellis, but when the police find his body stabbed to death before drowning they suspect Eve to be responsible for Mellis' death. Keith realizes the truth when Dr. Peter Templeton, a psychiatrist Eve visited under the guise of a suicidal Alexandra, says that Eve's distinctive feature was a scar from her head from her assault. Keith threatens to confess to the police if she doesn't marry him, and although Eve marries him, she cheats on him openly with a younger man. With Keith's silence and Kate's decision to lie for her so Eve can be punished in Kate's terms, Eve is acquitted. However, Keith deliberately destroys her face during a laugh line removal procedure, making Eve devoted to Keith in fear that he will leave her and she will be alone, and Kate decides that that will be Eve's punishment. Meanwhile, Alexandra marries Dr. Templeton and they have a son named Robert.
The book closes after Kate's ninetieth birthday party with all her relatives present. Robert, now eight, is turning into a talented pianist. She tries to meddle with Robert's future, but is rebuffed by Peter. Kate relents, but offers to introduce him to a renowned musician Zubin Mehta, leaving the reader to wonder whether Kate will repeat her mistake on Tony's career.