Four freshmen navigate the terrors of adolescence at their first-ever high school party.
Benj (Mason Thames) is an incoming high school freshman eager to reinvent himself and wants to date his slightly older sister Alyssa's (Ali Gallo) friend, Bailey (Isabella Ferreira). His friends Eddie (Ramon Reed) and Connor (Raphael Alejandro) are also excited to make a new name for themselves, and their other friend Danah 'Koosh' Koushani (Bardia Seiri) is eager to live up to his older brother's reputation.Eddie's mother has a new boyfriend Dennis (Scott MacArthur), who is always picking on Eddie.Benj and Alyssa live with their mother Ms. Neilsen (Kaitlin Olson). Benj used to dress up as Stevie Wonder and sing songs but doesn't do that anymore as he wants to cultivate a "grown up" image.
Benj's assigned carpool, senior student Ruby (Thomas Barbusca) is always stoned. Ruby involves him in a fraudulent drug sale by selling vitamins to skateboarders instead of MDMA.Koosh convinces his friends to attend his older brother's party that weekend as their parents are out of town that weekend. While Eddie and Connor are reluctant, Benj jumps at the chance to pursue Bailey.
Benj narrates a story of how Bailey was spending the night with Alyssa and he found her alone in the kitchen when he came down for a midnight snack. They ended up talking for a long and during that Bailey's breast popped out of her night dress. Now Benj believes he has a chance with her.Katrina is the hottest girl in school and has 0.5 M followers in social media. Mr. Studebaker is a recently separated teacher and none of his friends want to spend time with him. He is invited to Koosh's party by other students.
When the trio arrives at the party, Koosh reveals his brother is only allowing one of them to attend, and Benj convinces the others to let it be him. When Bailey and Alyssa arrive at the party, Benj talks to them briefly before he's left alone and interacts with a group of rowdy older students. Meanwhile, chemistry teacher Mr. Studebaker (Bobby Cannavale) arrives and quickly becomes increasingly intoxicated.
Connor, bored at Eddie's house, convinces the latter to steal his mom's irritating boyfriend's Tesla to drive to the party. Dennis had taken Eddie's mother her birthday dinner at Nobu and then for a night for sex at the Four Seasons.When they arrive, popular girl Katrina (Loren Gray), who is severely intoxicated, gets in the car believing that they're her Uber. They get Taco Bell and Katrina passes out. Eddie nearly crashes the car after Katrina has very liquid diarrhea, which soon gets all over them and the back seat. Connor and Eddie debate leaving her at the fire department before eventually deciding to care for her and clean the car.Connor and Eddie wash up Katrina, change her clothes and put her in Eddie's bed at his home.
Benj catches Bailey just before she is about to leave and invites her to have a beer with him. Bailey wants Benj to sing at the party, but he panics and Bailey realizes that Benj cares more about his image than being himself.At the party, Alyssa is criticized by her ex-girlfriend Nicole for her extreme negativity towards others. Mr. Studebaker accidentally lights himself on fire and jumps into the pool. Ruby warns Benj that the skaters he ripped off showed up to the party. When confronted, Ruby blames Benj entirely and gets punched.
Before the skaters can attack Benj, Koosh's older brother Kayvon (Kayvan Shai) intervenes, and after Ruby attacks one of them with a cattle prod, a fight breaks out; Alyssa gets her nose broken by accident and Mr. Studebaker is inadvertently electrocuted. Running away, Benj and Bailey kiss and reveal mutual affection for each another. Meanwhile, Koosh orchestrates a meet cute with a girl named Gabrielle (Victoria Moroles) by pretending they are trapped in his family's indoor spa. Gabrielle agrees to being massaged by Koosh.After the massage, Koosh convinces Gabrielle to get into the hot tub with him for a recovery.
Benj socializes and dances with Bailey. The group of rowdy older students invite him to a room where they're snorting lines of what he believes to be cocaine. Peer pressured, Benj does a line only to discover it is Ketamine, causing him to enter into a Dissociative state. Bailey finds him, gets upset and leaves.
The police arrive and break up the party. Koosh's plan fails after slipping on water and injuring his shoulder.Koosh tells Gabrielle that he had a key the whole time and she leaves in anger, leaving him to care for himself.Koosh bonds with Alyssa who is also at the hospital with her broken nose. Mr. Studebaker attempts to drive home but is unable to because his car key fob has melted.
The morning after, after being berated by their mom, Benj confides in Alyssa. She comforts him, telling him to be himself as that is who Bailey likes. Katrina wakes up and attacks Connor and Eddie, then quickly recalls what happened and leaves in embarrassment.
Eddie finally stands up to his mom's boyfriend. At a pep rally, Katrina defends Connor and Eddie from bullies, then apologizes and thanks them for being kind to her and for their discretion. Inspired by Alyssa's advice, Benj sings Stevie Wonder to Bailey and asks her out in front of the school, which she publicly rejects. However, while leaving, she secretly turns and winks at Benj.
In an end credits scene, Principal Hutchens (Kim Hawthorne) fires Mr. Studebaker after a video of him partying with students comes to light.
