The following version of this book was used to create the guide: Kwan, Kevin. Sex and Vanity. Penguin Random House, 2020.

Lucie Churchill is in Capri for a luxury Italian wedding. She traveled with her older cousin, Charlotte, a chronic worrier. Lucie worried initially that she would not be able to attend the wedding due to a schedule conflict, so she is grateful to have some time away from her native New York City. Lucie and Charlotte meet Rosemary and George Zao when they complain about their rooms and the Zao's offer to switch rooms with them. Charlotte refuses.

Lucie finds time to explore the island with the soon-to-be bride, Isabel, without Charlotte's oversight. Lucie is incredibly attracted to George, Isabel's second cousin. When another wedding guest takes Lucie shoe shopping the next day, she witnesses an elderly man have an accident which reminds her of her late father's death. George follows Lucie to ask if she is okay, and he comforts her while the pair go on a walk.

The group of wedding guests sail to Positano to visit a luxury villa. Lucie enjoys being out on the open ocean because it reminds her of her father. Rosemary and George are also at the villa, and Lucie struggles to keep her distance from George. They kiss before they board the boats and return to Capri.

Isabel marries Dolfi in a lavish ceremony, and Lucie sneaks off with George. They kiss and more until Charlotte bangs on the door and shouts that somebody is recording them from outside. George chases after the perpetrator and destroys the footage. Charlotte shames Lucie for allowing herself to be caught in such a compromising position, potentially damaging her reputation. Charlotte forces Lucie to pack her bags and leave Capri.

The novel jumps forward five years and Lucie is now engaged to the billionaire Cecil Pike. His proposal is lavish and public, embarrassing Lucie's more conservative style. Cecil and his mother attend an engagement party at Lucie's cousin's Manhattan apartment.

Lucie continues working on her art and planning for her wedding until she hears that George Zao will also be spending the summer on the Hamptons near her. She is overwhelmed by the news and nervous that she still has feelings for him. Lucie and George continue running into each other throughout the summer while she grows more disenchanted with the idea of marrying Cecil. When Lucie and George end up alone, they kiss and she realizes that he is still in love with her. She pushes him away, resolving to avoid him.

Lucie is unable to hide from her growing feelings for George, and as she falls out with Cecil she questions her engagement. Lucie eventually decides to break up with Cecil, returning his ring. Lucie still tells herself that she wants nothing to do with George so he decides to quit his job and move away from New York to avoid her and nurse his own broken heart. When Lucie realizes that she loves George too, she talks to his mother and convinces him to come back. The novel ends with Lucie and George together in Capri planning their lives together.