Gregory Bridgerton believes in true love, having witnessed all siblings and his mother experience it in his lifetime. He believes he has fallen in love at first sight with the lovely Miss Hermione Watson. However, Hermione in love with someone else. In order to make Hermione fall in love with him instead, Gregory requests the help of her best friend, Lady Lucy Abernathy.
Feeling sorry for Gregory, Lucy agrees to help him. She advises him on Hermione’s attitudes towards men and the things that will get her to appreciate him as a suitor. In the meantime, Lucy’s fiancée, Haselby, returns and states that it is time for them to finally marry.
On the night of a ball, Hermione and Lucy's brother, Richard, are compromised and the two are made to marry. Gregory is miserable, thinking he has lost the love of his love. He gets drunk and accidentally kisses Lucy, realizing that he actually has feelings for her.
However, Lucy is still betrothed and the two agree to part ways. After a month, the two bump into each other and Gregory realizes that her wedding is to Haselby, a closeted gay man. Gregory confesses his feelings to Lucy, and she him, but she cannot break off her marriage as she is being blackmailed to marry by her Uncle Robert.
Still madly in love, Gregory crashes the wedding and begs her to not marry Haselby. However, Lucy cannot do this and rejects him publicly. Lucy ends up marrying Haselby but later tells Gregory of the blackmail. Unable to live without her, he kidnaps her after the wedding and the two plot together to expose Uncle Robert. After Uncle Robert has been revealed to blackmail Lucy, he is arrested. Lucy gets her marriage annulled and she marries Gregory instead. The two live happily ever after.
