Keith Reynolds is a high school music teacher married to Megan and living in a small town an hour and half from New York City. He gave up a career as a musician following the arrival of their daughter. Lauren is very nearly 18 and is a champion swimmer. In his spare time, he substitutes for a cello player in an orchestra and is applying for a permanent role. Keith finds his life frustrating, resents his job as a teacher, and his wife’s dismissal of his music playing. He wants to move back to the city and work as a musician, but his wife Megan refuses to consider this as she disliked the uncertainty of the income and the lifestyle.
The family is to host a foreign exchange student from England, Sophie, for one semester. When Sophie arrives, she is disappointed by the distance from Manhattan which she wanted to visit. Sophie’s mother died when she was very young and she was raised by her uncle and aunt. Her uncle introduced her to the piano but has recently died, affecting Sophie badly. Sophie tells her aunt that she is not practicing her music because she does not know who she is playing for anymore.
Sophie reveals to Keith that she is an accomplished musician and they bond over their mutual interest. While they are alone at the house, she tells Keith about the death of her uncle and that she wants to choose to play music. Sophie is unsure and has lost her purpose following her uncle’s death, so she does not play. Keith has chosen not to play for the sake of his family.
Keith and Sophie embark on a love affair, spending time together talking about running away together. Lauren discovers this and reveals her knowledge to Sophie by attacking her while she is asleep in bed. Sophie panics after Lauren’s attack and tells Keith she must leave. Keith tells her he will run away with her. They plan to meet in New York City after a performance, packing their things.
Lauren, angry at her father and having been spurned by Aaron, gets drunk and crashes her car. Meanwhile, Megan discovers Keith and Sophie’s affair and their plan to run away. While she is smashing things around the house in anger, she gets a call telling her Lauren is hurt and in hospital.
Following his performance, Keith meets up with Sophie. They load their things in the car and are smiling at each other in happiness. Suddenly Keith receives a text message from Megan telling him that something has happened to Lauren. He appears at the hospital where Megan tells him she does not know how Lauren is.
The film ends with the family having a photo shoot. Lauren is fine but has a scar near her eye. Keith has decided to return to his wife and Sophie has gone.