In the late 1700s, the Duke of Hastings is ecstatic when his wife gives birth to a male child after fifteen years of miscarriages and stillborn births. The child is named Simon Basset, and he will one day inherit the title of Duke of Hastings. The duchess dies from complications during childbirth, and the duke leaves Simon in the care of a nurse as he goes about his business. When the duke visits Simon two years later, he is dismayed to find that Simon is not yet talking. Two years later, when he visits again, Simon can speak, but he has a stutter. The duke calls Simon an idiot and is furious that Simon won’t be fit to take on his role. Simon’s nurse helps him learn to speak without a stutter, and when Simon is eleven, they go to visit the duke in London. There, Simon’s father rejects him again, and Simon vows to be the exact opposite of his father.

The story moves to the year 1813. Daphne Bridgerton, the eldest daughter in the Bridgerton family, has been looking for a suitable husband for two years. She feels that most men view her as a friend rather than a potential mate, and she hopes that she will marry a man for whom she feels genuine affection. As one of eight children, Daphne hopes to have many children of her own one day. While at a ball, Daphne is taken aside by a man who has already proposed to her twice. When he refuses to leave her alone, Daphne strikes him and knocks him out, only to realize that Simon Basset, the new Duke of Hastings, has been watching their entire interaction. 

Simon realizes that Daphne is the sister of his friend Anthony Bridgerton, and Daphne says that she has heard of Simon’s wild reputation. They return to the ball and dance together. As they dance, Daphne reveals she would like a husband and children but has not found an acceptable suitor. Simon tells Daphne that he never wants to marry or have children. Simon then suggests that he and Daphne feign a courtship so that he won’t be bothered by society mothers trying to marry their daughters to him and Daphne will seem like more of a romantic option to other men. Daphne agrees to the plan, but Anthony becomes angry when he sees his sister with his wild friend. Later, when Anthony confronts the couple, they let him in on their ruse. Anthony is opposed to their plan, still fearing for his sister’s reputation, but he agrees to keep quiet about it on the condition that Daphne and Simon never be alone together.

Daphne and Simon become friendly during their pretend courtship, and they begin to feel a mutual attraction that they know they cannot act on. At one ball, Daphne and Simon take a walk in the garden and end up kissing. Anthony catches them and angrily says that he will duel Simon unless he marries Daphne. Simon responds that he can’t marry Daphne, as being married to him would destroy her dreams. At home, Daphne’s brother Colin tells her that she and Simon were seen going into the garden together, and Daphne understands that her reputation is at stake. 

Daphne knows that Anthony is angry enough to kill Simon, and she and Colin rush to stop the duel. Once there, Daphne tells Simon that her reputation will be ruined if he doesn’t marry her. Simon agrees to marry Daphne but tells her that he cannot have children. Daphne quickly replies that she will marry him anyway. The night before the wedding, Daphne’s mother attempts to tell her what will happen when she and Simon consummate their marriage, but her explanation is very vague. She tells Daphne that the act, if performed enough, will lead to a child, and Daphne wonders if Simon will be able to consummate the marriage if he cannot have children. 

After the wedding, Daphne and Simon stop at an inn on the way to Simon’s ancestral home in Clyvedon. Daphne feels embarrassed at how little she knows about marital relations. When Simon realizes that Daphne wonders if he can’t consummate the marriage, he assures her that he is more than capable. They make love, but Simon withdraws before he ejaculates.

After Daphne and Simon settle in at Clyvedon, Daphne visits with the housekeeper, Mrs. Colson, and Daphne learns about Simon’s childhood stutter and his father’s cruel rejection of him. Mrs. Colson also mentions the former duke and duchess’s struggles to conceive, saying that a man needs to provide a “strong, healthy seed” to make a child. When Daphne and Simon next have sex, she realizes that when he withdraws, he’s doing so in order to prevent getting her pregnant. She suddenly understands that he’s capable of having children but is choosing not to. When Daphne angrily accuses Simon of taking advantage of her ignorance, he explains that he refuses to have children because he wants his family title to die with him. After another argument, Simon goes to a pub and gets drunk. When he returns to Clyvedon, he and Daphne make love, but this time she holds him down so that he cannot withdraw. Angered, Simon abandons Daphne and goes to another one of his properties.

Daphne leaves Clyvedon as well, going to Simon’s Hastings House property in London so she can be closer to her family, who are confused by Simon’s absence. While there, Daphne realizes that her period is late and becomes convinced she is pregnant. Anthony is furious that Simon has abandoned Daphne and goes to the country to see him, bringing with him a letter from Daphne that lets Simon know she is pregnant. Simon returns goes to London, but upon reuniting with Daphne, he learns that she was mistaken and that she isn’t pregnant after all. Daphne asks Simon if he ever considered whether he truly doesn’t want children or if he just wants to spite his father. Simon ultimately realizes that he wants to live for himself instead of his father. Four years later, Daphne gives birth to their fourth child and first son, David. Simon knows he will love his son no matter what, just as he does his three daughters.