A woman named Jane (Kate Bosworth) moves to an island in Italy with her husband Leonard so he can play Viola and she can write. Her husband is very serious, and must work all the time. There, she meets a young man named Caleb who takes her around for a day, showing her how it feels to be young and free. She meets her husband for lunch the next day, and tells him how great it was to have fun and feel 19 again. Then, as they are about done with lunch, Caleb shows up and sits down to talk with them. Jane is thrilled, and introduces Caleb to her husband. He pulls out a cigarette, and offers it to Jane. Jane accepts, and this angers Leonard because he didn't know prior to this that Jane smoked. Leonard, trying to rush the situation, ask for the check and leaves with Jane. Jane walks Leonard halfway to work, and then she goes off on her own.
Caleb follows Jane and finds her after she leaves Leonard. They walk into an alley and Caleb states that he thought about her all night and came to this area on purpose in order to find her. He leans in to kiss her, but she is hesitant. They begin to kiss. Jane pushes Caleb away and accuses him of being someone who likes to seduce women. She runs away from him, and tells him not to follow her.
The next few weeks or so are hard for Jane. She starts to notice that her husband is not noticing her, and also that she as become too serious. She finds where Caleb lives and hopes to spend the day with him in order to become less serious. They do lots of fun things like dancing and swimming. That night, they have sex. Jane feels good about it however, and spends the night with him. The next morning, he get home with her husband at the door concerned about where she was. Jane says that they need to talk, but he says he has to go to work and cannot be late. This angers Jane because she realizes Leonard doesn't even see what's happening.
Jane now spends all her free time with Caleb, and it sparks new ideas for her writing. However, her husband doesn't seem to be interested still. Caleb tells Jane about to people he met who are traveling to Tibet. He wants to join them on their travels, and asks Jane to come with him.
Jane tells Leonard that she doesn't think he loves her anymore because she can't have children and that's all he ever wanted. Leonard denies this, but Jane is so angry that she admits to having an affair. She tells him it is Caleb, which disgusts him. He ask her if she has been sleeping with him, in which she replies "What do you think?". Leonard thinks Jane is only having sex with Caleb because she is mad about not being able to have kids. He gives her a train ticket and tells her to work things out with Caleb, and then meet him so they can go home together.
Jane spends another night with Caleb. When she wakes up, she packs and kisses him goodbye as he tells her about his plans for Tibet. Jane goes to the train station, but doesn't go with Leonard. She boards a different train.