Amy, portrayed by Kaitlyn Dever, and Molly, played by Beanie Feldstein, are two inseparable high school seniors who have navigated life as best friends since childhood. Despite their close bond, they often find themselves labeled as pretentious by their peers. As they approach the final day of high school, both girls are set for Ivy League schools next year. Molly, taking her role as class president to heart, is serious about her responsibilities, while their principal, Jason Sudeikis, and Miss Fine, their devoted teacher Jessica Williams, look on.
Amy, who has been openly gay for two years, harbors feelings for a girl named Ryan, portrayed by Victoria Ruesga. Although Molly encourages her to reach out to Ryan before they graduate, their plans take a drastic turn. On the eve of graduation, Molly overhears some classmates gossiping about her in the bathroom. When she learns that, despite not focusing on academics like she and Amy did, those classmates also secured spots at reputable colleges, she becomes overwhelmed. Feeling a wave of panic, Molly lashes out, insisting that they should have enjoyed their high school years more. This prompts her to suggest they attend a graduation party hosted by Nick, a jock played by Mason Gooding.
Initially hesitant, Amy ultimately agrees. However, the duo quickly realizes they are clueless about the party's location. Molly reaches out to Jared, a wealthy classmate, played by Skyler Gisondo, who has a crush on her but whom she deems a "loser." Jared leads them to his unguarded yacht party, where they cross paths again with Gigi, a wild partygoer played by Billie Lourd, who encourages them to partake in some strawberries, unknowingly leading them to trouble. Although Amy suggests returning home, Molly initiates a "Malala," a term they created for unconditionally supporting each other, and they continue their adventure through the night.
Their next ride comes from none other than Principal Brown himself. After an embarrassing incident involving explicit content played through his car speakers, he drops them off at what they think is Nick's party. To their surprise, they find themselves at George's house, where a murder mystery gathering is in full swing. There, Gigi reveals the strawberries were actually laced, sending Amy and Molly into a psychedelic spiral where they imagine themselves as dolls. After escaping George's place and tracking down Nick's real party, they manage to modify their plans slightly.
Arriving at Nick’s party, Amy seeks out Ryan while Molly pursues Nick, with hope for a romantic connection. However, Amy's heart shatters when she discovers Ryan kissing Nick. Frustrated and hurt, Amy expresses her frustrations to Molly, revealing she's considering a gap year in Botswana—an idea that Molly's controlling tendencies have overshadowed. This leads to a loud confrontation in front of their friends, causing Amy to storm off to the bathroom, where she has an unexpected encounter with classmate Hope. Initially at odds, the two share a kiss that quickly goes awry when Amy becomes sick.
As the party spirals into chaos and police arrive, the guests flee. Molly, separated from Amy, finds herself being driven home by Triple A, played by Molly Gordon, another classmate with a reputation for being wild. On graduation day, Molly is filled with regret over the events of the night before. She soon learns of Amy's unexpected heroics at the party, where she caused a distraction that led to her arrest. Determined to mend their friendship, Molly visits Amy in jail for an honest reconnection, leading to their reconciliation.
In a twist, they discover that the pizza delivery driver is a notorious killer, trading this reveal to secure Amy's release. With a newfound sense of freedom, they make it to graduation, where Molly embraces the moment by kissing Jared on stage and delivering an impromptu valedictorian speech that leaves everyone in awe.
Days after graduation, as Molly helps Amy prepare for her journey to Botswana, Ryan pays a surprise visit to give Amy her number, signaling new beginnings. As Molly drives Amy to the airport, they share an emotional farewell, but not before Amy leaps in front of the car suggesting they grab pancakes before her flight—an opportunity Molly eagerly accepts. Their friendship, resilient through ups and downs, stands strong as they commit to creating memories even in the fleeting moments they have left.
