Griffin, Everett Blunck is a 14-year-old aspiring playwright who dreams of moving to New York City and staging his plays on Broadway. For his summer vacation, Griffin is at work on his latest piece, a divorce drama he describes as "Who's Afraid of Virginia Woolf? meets American Beauty" titled Regrets of Autumn. The play draws from the marital troubles between his mother Helen, Melanie Lynskey, and father Bill, Michael Esper.
His best friend Kara, Abby Ryder Fortson, offers to be the director, while their friends Winnie, Johanna Colón, Pam, Alivia Bellamy, and Tyler, Gordon Rocks fill out the cast. Kara also promises to stay connected by phone, even as she spends part of the summer in Maine with her new boyfriend.
One day, Griffin notices that Helen has hired a 25-year-old handyman named Brad, Owen Teague, to work on the family pool. Brad is an aspiring actor who recently moved back from New York City after his acting career stalled. Griffin is initially irritated by the loud techno music Brad blasts outside while working, but he soon finds himself developing a crush and even offers him liquor from his parents’ cabinet to get closer. The two young artists discover a shared love of art, and a tenuous friendship begins to form.
Griffin stakes out Brad at a bar, only to learn that Brad is there with a girlfriend, Chloe, Kathryn Newton. Undeterred, Griffin tries to find ways to involve Brad in his play. He abruptly fires Tyler and asks Brad to take over the role, and Brad tentatively agrees after Griffin promises to pay him; Brad’s addition to the production shifts the writing and changes the dynamics among the remaining cast. When Kara voices concerns to Griffin about these changes, he lashes out at her and her boyfriend, further straining the group.
In an attempt to distance Brad from Chloe, Griffin sends a sexually explicit email to Brad under the fake persona of an older woman named "Glenn Bening." Chloe sees the message and breaks up with Brad, sending him into a tailspin. A frustrated Brad vents to Griffin by a lake, admitting that he feels like a failure who had to move back to the suburbs, and that Griffin may be his only real friend in this town. Griffin reassures him that he is not a loser and that Brad is the best thing that has happened to him.
The next day, Brad skips rehearsals and Griffin learns that Brad has moved back to New York City. Brad sends a text apologizing for not being able to stay in Griffin’s production, saying that the breakup with Chloe has pushed him to rethink his life and pursue his dreams again in NYC. Griffin impulsively hops a train to New York and tracks Brad down at his apartment. There, he confesses his feelings again, including hopes that the two could share a place when Griffin turns eighteen and make art together. Brad makes it clear that he is not gay and tells Griffin to leave.
Griffin is distraught and phones his mother, Helen, who has been frantic over his disappearance. They eventually reconcile, and Griffin admits that he transferred money from Helen’s bank account to Brad to help him, a gesture Helen slowly forgives. He also makes amends with Kara after telling her about Brad. Griffin worries that the play may be doomed because of how his behavior alienated the cast, but Kara urges him to repair the rift with the others. After Griffin sincerely apologizes to Tyler, Pam, and Winnie, they all agree to rejoin the project.
As summer ends, the friends debut the play at a community center. Griffin tweaks a few lines to reflect his growth and his move past Brad. Winnie introduces him to her friend Mark, Ian Hernandez-Oropeza, who expresses genuine appreciation for Griffin’s work. Griffin then invites Mark to the cast afterparty at his house, and when he sees all his friends happily swimming in the pool, he decides to join them.
