The following version of this book was used to create the guide: Serle, Rebecca. One Italian Summer. Simon & Schuster, 2022.

When the novel begins, Carol Silver’s family and friends are sitting shiva for her. Carol passed away after a prolonged illness. Her daughter, Katy, and husband, Chuck, are devastated. Eric, Katy’s husband, arrives at Chuck’s home towards the end of the day. The night before, Katy told him she wants a divorce.

A few days later, Katy moves back in with Eric, but still does not feel normal. She decides to go to Positano, Italy. Carol loved Positano; she went there as a child and then again as a young woman. Katy and Carol were supposed to go together. They had everything booked and ready to go before Carol’s death.

Katy does not want Eric to join her. She arrives at Positano alone and stays at Hotel Poseidon, where all the staff are warm and friendly. Katy meets a fellow American at the hotel named Adam. Adam works for a developer who is trying to buy Hotel Poseidon. The owner, Marco, is against the hotel being bought but his daughter, Nika, thinks it is the hotel’s only hope for survival.

On Katy’s first full day in Positano, she spots a younger version of her mother dropping off a package at Hotel Poseidon. It really is Carol when she was around 30 years old—the same age Katy is. Carol is delighted to meet another American woman travelling alone. The two arrange to meet at the dock later that day.

Katy is overjoyed to have her mother re-enter her life. The two women take a boat to a nearby restaurant with a friend of Carol’s named Remo. Katy wonders whether Remo and Carol are together. They spend the day eating and lounging.

Back at Hotel Poseidon, Katy has dinner with Adam. She enjoys being around a new man who knows nothing about her. Adam calls her cute.

The following day, Katy runs into Carol while on a hike. Katy invites her to breakfast, but Carol says she is busy coming up with a design proposal for a famous hotel in Positano called the Sirenuse. They arrange to meet for dinner. Katy finds a message waiting for her from Adam at the Hotel Poseidon. The two have lunch and go sight-seeing. Katy finds herself attracted to Adam. That evening, a bus arrives to take Katy and Carol to dinner. Katy tells Carol about her mother’s death and crumbling marriage with Eric. Carol advises her not to be afraid of change. They go dancing with Remo afterwards. Carol assures Katy that she and Remo are just friends.

When Katy returns to Hotel Poseidon after her night out with Carol and Remo, she finds Adam on the terrace. He fetches her some water. Katy kisses Adam, then pushes him away, remembering that Eric awaits her back home.

The next evening, Adam takes Katy to dinner at a fancy hotel called Il San Pietro. He reveals that he first came to Positano with an ex of his. Adam has a hard time maintaining long-term relationships because his work demands that he travel a lot. Adam touches Katy’s arm but she says she cannot kiss him again.

Katy spends the entirety of the following day searching for Carol, to no avail. The day after that, she runs into Adam while on a hike. She asks him to accompany her to Capri. After a delicious lunch, they spend the day napping in the sun and swimming. Adam takes her to Faraglioni, an archway of rocks famous for bringing good luck to lovers who kiss beneath it. He does not kiss her but he does hold her hand and call her beautiful.

Two days later, Adam takes Katy to Naples. At first, Katy does not see what Adam loves about dirty, chaotic Naples but soon recognizes the sense of community and love there. Adam tells her his sister died when he was young. Seeing his mother’s pain made him afraid of fully dedicating himself to another person.

The next day, Katy finds Carol outside Hotel Poseidon. The two head to Carol’s apartment for dinner. Katy asks Carol about Carol’s childhood and parents—something she never did while Carol was alive. Katy asks Carol for advice on her marriage but Carol only tells her that Katy knows best what to do. After spilling some oil on her dress, Katy heads to Carol’s room to change. Katy spots a photograph of herself as a baby and realizes that Carol abandoned her to come to Positano alone. She yells at Carol, trying to explain that she is Katy, Carol’s baby. Carol does not understand.

Katy runs out of Carol’s apartment and heads back to the hotel. She finds Adam near her room and pulls him inside. They have sex. The next morning, Adam leaves in a hurry for a meeting at the Sirenuse. Katy finds Carol at their usual hiking spot. Carol explains why she left her baby. She felt overwhelmed by becoming a mother and wife so soon. She needed time to figure out who she was outside of her marriage and family. When Carol leaves for her meeting at the Sirenuse, Katy realizes that Adam is from Carol’s time, not her own.

Katy rushes back to Hotel Poseidon to ask Nika what year it is. Nika says 1992. Nika hands Katy a letter Carol tried to mail but which got sent back. Katy locks the letter in a safe before rushing to the Sirenuse, determined to stop her mother from meeting Adam and potentially never returning to America. Once there, Katy realizes she has no right to interfere in her mother’s chance at happiness. She meets Adam for lunch later and advises him not to buy either Hotel Poseidon or the Sirenuse. She thinks he should keep Positano a place he loves, not a place for work. Back at Hotel Poseidon, Katy advises Nika to invest in Apple and Starbucks stocks.

Carol shows up at Hotel Poseidon. The two head to a nearby restaurant. Carol doubts her designs will be chosen for the Sirenuse. Katy reassures her that she will make an excellent mother.

The next day, Eric arrives at the Hotel Poseidon. Katy is relieved to see him. He declares that he wants a future with Katy and says he wishes he came with her to Positano in the first place. While Eric showers, Katy speaks to Chuck on the phone. She tells Chuck she knows why Carol came to Positano. He says letting her go was the best thing he ever did for their marriage. When Eric emerges from the shower, Katy tells him she loves him and wants a future with him, too. They have sex. The couple decides to stay in Positano for a few more days. They release Carol’s ashes at Faraglioni.