After embarking on a post-graduation road trip, Elle Evans (Joey King) finds herself caught in a dilemma between attending Berkeley or Harvard, while her boyfriend Noah Flynn (Jacob Elordi) has already started making plans for an off-campus apartment for the two of them. Complicating matters, the parents of Noah and Lee Flynn (Joel Courtney) reveal their intention to sell the beloved beach house where the friends spent their youthful summers. To assist with the sale, Elle, Noah, Lee, and Lee's girlfriend Rachel (Meganne Young) decide to spend the summer there.
During this nostalgic season, Lee aims to create opportunities to bond with Rachel, who is heading to a different college. Meanwhile, Elle grapples with the impending deadline from Berkeley, ultimately deciding to join Noah at Harvard, which frustrates Lee. To mend things, Elle promises Lee that they will complete their beach bucket list of adventurous activities. This includes everything from swimming with sharks, atomic wedgies on Noah, cliff jumping, skydiving, sandcastle building, pie-eating contests, brain-freeze challenges, and even helium karaoke.
As summer progresses, Chloe Winthrop (Maisie Richardson-Sellers), an old friend of Noah's who is facing her own family struggles, arrives at the beach house, intensifying tensions. Elle, who once suspected Noah of cheating with Chloe, finds herself involved in a heated argument with them after Chloe makes a light-hearted remark about Elle's gaming skills. Adding further drama, Elle encounters Marco Peña (Taylor Zakhar Perez) at the beach, which sparks jealousy in Noah, leading to dialogue about double standards in their relationships.
Their rivalry escalates at the go-kart track when Elle asks Noah to dress up as Wario, but he refuses, allowing Marco to step in instead. After Noah’s unexpected defeat by Marco, tensions run high, resulting in him confronting Elle about Marco's lingering feelings for her. Encouraged by Chloe, Noah reconciles with Elle, but Marco is relentless, showing up at their Fourth of July party, escalating their feud as he physically confronts Noah, who opts not to retaliate.
Elle's emotional turmoil deepens when Lee appears to move on, forming a close friendship with a guy named Ashton, who has just completed his first year at Berkeley. Feeling displaced, Elle grapples with the concept of friendship and loyalty to Lee. Marco confesses his feelings for Elle, but she is not interested, drawing her focus back to Noah. Complicating matters further, Elle is challenged by her father's new girlfriend, Linda, who she learns was friends with her late mother. Eventually, Elle accepts Linda, as her father explains that he has devoted years to Elle and her brother Brad, now it’s time for him to pursue happiness.
As she wrestles with her decisions about college, Noah reveals his concern that she may be choosing Harvard purely for him; he ultimately breaks things off so Elle can focus on what she truly wants. This heartbreak leads to a missed opportunity to complete one of their bucket list activities, Dance Dance Revolution, resulting in a clash with Lee, where both express their frustrations. Lee accuses Elle of prioritizing Noah over their friendship, while Elle argues that she has been trying to appease everyone.
Later, comforted by Noah and Lee’s mother, Elle is advised to reflect on her true desires and make a college choice accordingly. Meanwhile, the parents decide against selling the cherished beach house, realizing its importance in their children's lives. With Rachel witnessing Elle and Noah’s struggles, she decides to end her relationship with Lee, yet they both hope for reconciliation in the future. Marco makes amends with Elle as well, establishing an amicable parting before Elle realizes that focusing on her happiness is essential.
She boldly applies to the University of Southern California for Game Design, where after impressing the admissions team with her concept for a fantasy esports league, she is accepted. Excited, she shares the news with Lee, who is thrilled for her.
Fast forward six years, Elle is now forging her path as a game developer, having maintained her deep friendship with Lee, who has rekindled his romance with Rachel. In a pivotal moment, Elle encounters Noah, who shares his upcoming job offers in Los Angeles and New York. While immediate decisions must be made, he suggests a motorcycle ride when he’s back in town. Their parting moment implies a lingering affection as they look back at each other, hinting they have never really moved on from their love.
The film concludes with a vibrant scene of Elle and Noah riding down the California coastline on their motorcycles, filled with laughter and joy, symbolizing Noah’s choice of the LA office and their choice to rekindle their romance, now that they have both matured.
