Plot
After her mother's death, 17-year-old American Lina Emerson spends the summer in Rome before starting college. Although her extroverted best friend Addie wanted to join her, she has to go alone to honor her mother Hadley's last wish. Lina is not only uninterested in face-to-face interaction but also not on social media as well.
As she arrives in Italy, Lina is to stay with her mother's friend, Francesca. They then visit the latter's cousin Howard Riley's prep school graduation party where she briefly meets both Lorenzo and Alessandro.
Arriving at Francesca's, Lina is given her mother's diary from when she visited Italy at the same age and left to get settled in. As she's trying to sleep off her jetlag, Alessandro calls and invites her to an opera fundraiser that night.
Francesca gives Lina a makeover, and dresses and coaches her. At the opera, Lina admits to Ale she has little life experience, which doesn't dissuade him. He gets her to chase him through off-limit areas of the building, until security catches them.
Ale's banker father insists he meet important contacts, so Lina leaves. Flustered, she bumps into Lorenzo, who is working with the event's catering, getting gelato on her. Recognising her from the graduation party, he offers her clean clothes and a lift.
On the way, Lorenzo takes Lina to get pastries from a secret bakery. As he's leaving her at Francesca's, Ale shows up and invites her to go swimming the next day at noon.
In the morning, Howard shows Lina some of Hadley's photos, some of which she recognizes, and gives her her camera. She spends a few hours snapping photos until she's due at Ale's. They take one of his dad's many cars out to a stream with a waterfall and he convinces her to jump into the pool below. Exhilarated, after he pledges exclusivity, Lina has her first make out session.
Elated, Lina tells Addie about it. Spying on Ale's social media account, however, there is no mention of her but a recent photo with someone else and not with his dad as he'd told her. Lina then confronts Ale.
The next day, Lina goes to the countryside with Fran and Howie for a meal at his colleagues', Lorenzo's moms. She catches Lorenzo doing a practice run for his examination to enter a culinary school. Lina is helping to make the gelato when his possessive girlfriend interrupts by making out with him.
At the meal, Lina confronts Howie, believing he is her father. Despite her misinterpretation of the diary, he still offers to step up as her father because he was in love with Lina's mother. She later discovers that her mother's photography teacher, Matteo Fossi, is her biological father.
Finding Fossi's studio in Florence, Lina grabs the train and coincides with Lorenzo. They encourage each other, agreeing to return to Rome together. At the studio, she introduces herself as Fossi's daughter, but is told he's out. Lina barges into his office only for him to ignore her. She leaves, taking a large photo of her mother from Fossi's gallery display.
Lina and Lorenzo commiserate their unsuccessful missions and kiss, although she tells him it was a mistake once back in Rome, due to the timing. As she announces she's returning to the US early, Fran calls Addie, their emergency plan. Arriving quickly, she insists they stay to have fun. Addie gets them an invite to Ale's graduation party. There, Lina realises Ale will always follow his family's wishes and discovers Lorenzo is heading to Paris.
Addie and Lina hurry to the station, where she wishes him luck and says the kiss wasn't a mistake. Meeting with Howie, she gives him her mother's love lock she found. As she's deferring college for a year he asks if can act as her adoptive dad.
One year later, Lina finds Lorenzo in Rome in front of the secret pastry shop. He reveals he'll be taking over, as the woman who ran it retired. Lorenzo invites Lina to his grandmother's in the countryside, so they go on her Vespa.
