In Brooklyn, 23-year-old Eleanor finds herself at a turning point after breaking up with her unreliable and unfaithful musician boyfriend, Dennis. Facing the harsh reality of moving out of his apartment, she seeks solace at a friend's place but soon faces the wrath of her ex. In a heated confrontation at her workplace, Dennis's tirade results in Eleanor losing her job, leaving her even more isolated. Disappointed by her family's refusal to help her in this tough time, she turns to her friend one last time before embarking on her search for temporary employment.
Meanwhile, in the Upper West Side, 12-year-old Reggie is a prodigious cellist and intellectual who leads a lonely existence. His busy parents often delegate his care to various sitters, the latest of whom had to leave for Panama. In response, Reggie's mother, Barbara, places an ad for a temporary caregiver, and this is where Eleanor comes into the picture.
Despite Reggie's incredible talents, he struggles against the perceptions of those around him. He cleverly navigates his mother's expectations by bribing those in his life, creating the illusion of being well-behaved. When Eleanor meets Reggie, she is moved by his original composition, "Like Sunday, Like Rain," and an unexpected friendship blossoms between them. As summer camp approaches, she encourages Reggie to attend, but he chooses to stay in the city instead.
Eleanor's tumultuous relationship with Dennis continues to haunt her. He becomes increasingly obsessive, attempting to reconcile and get back together, but Eleanor stands firm in her decision to end things. After an unsettling incident involving a broken guitar, Dennis vows revenge, but he fails to confront Eleanor again.
During a day out at the park, Reggie becomes intrigued by Eleanor's world. However, trouble brews when Eleanor learns of her father's terminal illness, prompting a trip back to her hometown. What starts as a brief visit soon transforms into an emotional journey for both of them, as Reggie witnesses Eleanor's strained family dynamics. Her sister works in a questionable bar, while her mother and uncle seem apathetic toward Eleanor's father's condition. Seeking peace and quiet, Eleanor takes Reggie to a hotel, where she opens up about her past relationship with Dennis and shares her dreams of studying at Juilliard.
That night, Reggie decides he will compose a piece featuring Eleanor, cementing their bond even further. The following day brings mixed emotions when Eleanor visits her father, and Reggie observes the depth of her heartache. Disillusioned by his family's indifference, Eleanor has a heated argument with her uncle, ultimately deciding to leave for good and returns home with Reggie.
As summer winds down, Reggie's attachment to Eleanor strengthens, but the reality of her temporary job looms over them. A new caregiver arrives, leading Reggie to struggle with the thought of Eleanor leaving. She feels a strong need to return home to regain stability in her life, and they share a heartfelt embrace filled with promises to stay connected. With a gentle kiss, Eleanor bids farewell, leaving Reggie to navigate his privileged yet lonely existence, now filled with thoughts of her.
In a gesture of affection, Reggie arranges a gift for Eleanor—a cornet featuring his revised notes for "Like Sunday, Like Rain." Committing to his music once again, Reggie plays the cello, while Eleanor thoughtfully plays her part from a distance, forever connected through their shared experiences.
