One winter day, Barnes Hawthorne is enjoying a moment on the roof of his friend PJ's house, indulging in some cannabis, when his gaze is drawn to a girl across the street. PJ identifies her as Remi Aguilar, just finishing a college admissions interview. Intrigued by her, Barnes finds himself captivated, but PJ admits that he doesn’t know her very well. This fortuitous encounter leads to another serendipitous meeting at a New York train station, where Barnes spots Remi again as she prepares for a tour of Columbia University. They strike up a meaningful conversation on the train, discussing their favorite band, The Talking Heads, and sharing aspirations. Remi dreams of attending Harvard to become a lawyer, while Barnes, lacking clear ambitions, contemplates a gap year. She offers him thoughtful suggestions on how to utilize his time, including volunteering with sea turtles in Costa Rica. Their budding connection is interrupted when Barnes impulsively asks her out on a date, but she is abruptly struck by a cyclist and requires stitches. At the hospital, Remi gently declines his invitation, explaining that she's not ready to involve someone like him in her life at that moment.
As spring unfolds, Remi finds herself torn between following her dreams at Harvard and spending a year volunteering in Costa Rica with sea turtles—a choice that brings her parents into her room for an unsolicited sex talk on prom day, despite her insistence that her prom date is merely a friend. Her mother hands her a few condoms, insisting she be prepared "just in case." Meanwhile, at Barnes's home, he seeks permission from his mother to borrow the car, intending to take his ex-girlfriend, Erica, to prom after their recent breakup. During prom, when Remi's date sees the condoms in her purse, he wrongly assumes she is ready to take their relationship to a more serious level, referring to her as a snob when she clarifies otherwise. At the prom, Remi meets PJ for a joint "on the house," ultimately running into Barnes. They discover Erica's invitation was purely to enrage her ex, which brings Barnes and Remi closer together as they find joy in dancing to "Burning Down The House." As the night progresses, Barnes suggests they escape for sushi during a slow song, where he reveals his fluency in Japanese from his time living in Japan with his Army medic mother. Inspired by their earlier conversation, he admits he might volunteer in Costa Rica. After dinner, they head to his house where they share a moment smoking the joint Remi procured. Despite a growing romance, she reminds him of her impending departure for Harvard, leading them to make tentative plans for a summer together.
On July 4th, amidst the celebrations, Barnes, Remi, and PJ sit on the rooftop, witnessing Remi's father paint their house crimson in honor of her upcoming journey to Harvard. In secret, however, Remi plans to volunteer in Costa Rica with Barnes instead. Encouraged by him, she confronts her parents about her plans, but their reaction is far from supportive as they express disapproval and attempt to talk her out of it, fearing she is jeopardizing her future. Even after they ground her, Remi remains resolute, leaving with Barnes and PJ to celebrate at a lake house party. However, things take a turn when, after drinking too much, she crashes PJ's jeep into a mailbox, leading to a tense argument with Barnes at the lake and ultimately resulting in their breakup.
As fall arrives, Remi settles into her new life at Harvard, only to stumble upon an Instagram post revealing that Barnes is also in Boston, working as an assistant for a VP at a record label and touring with a band. They reconnect on campus, sharing bittersweet feelings about their breakup and recognizing that parting might have been what was best for them. Remi takes the initiative to invite Barnes to a Halloween party, but he has to attend a concert that night. Encouraged by her friends, Remi decides to express her emotions and sneaks into the concert, only to be chased by security. Barnes comes to her rescue, and she confesses her lingering feelings, requesting another chance between them despite acknowledging the challenges ahead. However, Barnes gently declines, believing it's best to remain friends, leaving Remi heartbroken.
Later, the band on the tour bus encourages Barnes to confront his own feelings. He confesses to them about Remi, realizing he made a mistake turning her down. They rally together to help him serenade Remi outside her dorm, prompting her to peer out her window, seemingly lost for words. Ultimately, she comes outside, and amid unspoken glares, they share a heartwarming reunion with a kiss, rekindling the connection that had once been so strong.
