Griffin Nafly [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 works 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 is inspired by the marital troubles between his mother Helen [Melanie Lynskey] and father Bill. 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. He is dismayed to learn that Kara will be spending part of her summer in Maine with her new boyfriend, but she promises to stay updated by phone.
One day, Griffin sees Helen has hired 25-year-old handyman Brad Rizzo [Owen Teague] to work on the family pool. Brad is an aspiring actor who has just moved back from New York City after his acting career stalled. Griffin is initially annoyed with Brad when his playwriting is disrupted by the loud techno music he plays outside while working. However, he begins to develop a crush on the oblivious Brad and offers him liquor from his parents' cabinet to get closer to him. Brad and Griffin develop a friendship over their shared interest in art.
Griffin stakes out Brad at a bar, but is disappointed to find that he is there with a girlfriend, Chloe [Kathryn Newton]. Nevertheless, he looks for ways to get Brad involved with his play. He abruptly fires Tyler and asks Brad to take over the role. Brad tentatively agrees to do the play after Griffin says he will pay him; his addition to the play causes changes to the writing and the dynamics among the remaining cast. When Kara voices concerns to Griffin about the changes, he insults her and her boyfriend.
In the hopes of breaking up Brad's relationship with Chloe, Griffin sends a sexually explicit email to him under the fake persona of an older woman named Glenn Bening. Chloe sees the email and breaks up with Brad, sending him into a tailspin. A frustrated Brad vents his feelings to Griffin one day by a lake. He sadly confesses that he feels like a failure who had to move back to the suburbs, and that Griffin is probably his only friend here. Griffin reassures Brad that he is not a loser and that he is the best thing that has happened to him.
The following day, when Brad does not show up to rehearsals, he goes to Brad's mom's house to find him. He discovers that Brad has moved back to New York City. In a text message, Brad apologizes for not being able to do Griffin's play, but says that his breakup with Chloe spurred him to rethink his life and make another go at his dreams in NYC. Griffin impulsively takes a train to New York and locates Brad at his apartment. When Brad expresses confusion at his presence, Griffin confesses his feelings for him, including his hopes that the two can get a place when Griffin turns eighteen and create art together. He also admits that he is behind the Glenn Bening email. A startled Brad says he is not gay; he then rejects Griffin and tells him to leave.
A distraught Griffin calls Helen, who has been frantic over his absence. As they reconcile, Griffin admits to transferring money from her bank account to pay Brad, which Helen haltingly forgives. He also makes up with Kara after telling her about Brad. Griffin is worried that the play may be over since his behavior alienated the cast, but Kara urges him to make amends with the group. After Griffin makes a sincere apology to Tyler, Pam, and Winnie, they agree to be in the play again.
At the end of the summer, the friends debut the play at a community center. Griffin has changed some of the lines to reflect him getting over Brad. Afterwards, Winnie introduces him to her friend Mark [Ian Hernandez-Oropeza], who expresses his enjoyment of Griffin's work. Griffin 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.
