In 1996, Stevie, a 13-year-old boy living in Palms, Los Angeles, navigates the challenges of a troubled home life, marked by a physically abusive older brother, Ian, and a single mother, Dabney. One fateful day, Stevie's curiosity draws him to Motor Avenue Skateshop, where he is captivated by the lively banter and camaraderie of the skaters outside. Enthralled, he returns the next day and, through a trade with Ian, acquires a skateboard. At the shop, he forms a bond with young skater Ruben, who introduces him to an eclectic group of friends: the charming leader Ray, the boisterous Fuckshit played by [Olan Prenatt], and the more reserved Fourth Grade portrayed by [Ryder McLaughlin]. Despite his lack of experience, Stevie is eager to fit in and emulate their reckless behavior and anti-social attitudes.
During a conversation, Ray dubs Stevie "Sunburn," signaling his acceptance into the group. However, this newfound camaraderie stirs feelings of jealousy in Ruben. As Stevie attempts an ambitious skateboard trick between two rooftops, he suffers a head injury, prompting concern from Dabney about his reckless choices and his association with the group. Nevertheless, Stevie is resolute in his decision to remain part of this new clique. Tensions rise when Ian confronts Fuckshit, yet he backs down before a potential fight can erupt. As Stevie delves deeper into this lifestyle, he starts to smoke, drink, and even experiments with marijuana.
At a party, he has his first kiss and a sexual encounter with Estee, an older teenage girl, highlighting the significant age gap between them. The situation escalates when a drunken confrontation with Ian leads to a violent altercation. In the aftermath, feeling isolated and despondent, Stevie resorts to self-harm, attempting to asphyxiate himself with a SNES controller cord. The following day, Dabney forbids him from associating with his friends, only to have Stevie defiantly reject her orders. Alienated from both his mother and brother, Stevie finds solace behind the skate shop, where Ray offers him comforting words about their shared hardship. Ray shares the struggles that his friends face: Fourth Grade's poverty, Ruben's abusive home life, Fuckshit's worsening behavior, and his own grief over the loss of his younger brother. Eventually, Ray takes Stevie on a nighttime skate adventure, and they find themselves falling asleep beneath the stars at the Santa Monica Courthouse.
A party at the shop subsequently unfolds, with Ray hoping to turn his skating passion into a career by courting potential sponsors. However, Fuckshit, under the influence, tries to undermine Ray’s credibility. After a night of heavy drinking, Stevie and Ruben's friendship deteriorates to the point of physical confrontation. Disheartened by their group’s lack of discipline, Ray asks everyone to leave. However, a persistent Fuckshit convinces the group to head to another party. In a moment of recklessness, Fuckshit crashes the car during a chaotic drive, resulting in Stevie being knocked unconscious and rushed to the hospital.
When he awakes, Stevie finds Ian by his side, offering him solace in the form of orange juice. As Dabney arrives, she sees Stevie's friends camped in the waiting room, prompting her to invite them to his room. Moved by their solidarity, a glimmer of reconciliation appears on the horizon. Meanwhile, Fourth Grade pulls out a camera to share a documentary-style film of their escapades, titled "Mid90s," capturing the essence of their youthful adventure.
