On the Upper East Side, once a wealthy and carefree teenager known as White Mike, played by Emma Roberts, now finds himself in a desperate situation, barely managing to survive as a pot dealer among his former classmates. Following the tragic loss of his mother, whose extensive medical treatment drained away the family’s fortune, Mike bears emotional scars that haunt him. His close friend, Molly, remains blissfully unaware of his illicit activities.
Mike’s connection to the underworld is through his supplier, Lionel, who is also tangled up in dealing a dangerous drug known as "Twelve" to Mike's cousin, Charlie. In a moment of desperation, Charlie attempts to rob Lionel but meets a grim fate when Lionel shoots him, also injuring an innocent bystander, Nana. Consequently, Mike's good friend Hunter finds himself wrongfully blamed and taken into custody for these heinous acts.
As the vibrant yet dangerous world of Manhattan unfolds, we are introduced to a variety of young characters at a party hosted by Chris, including Tobias, Yvette, Sara, and Jessica. During this gathering, Jessica makes a fateful decision to try "Twelve" for the first time, which spirals into addiction. Meanwhile, Claude, Chris' older brother and a sociopathic weapon enthusiast, returns home from rehab, triggering conflict with their mother, who threatens to involve the police.
Sara, seeking to make her birthday unforgettable, manipulates Chris into hosting an extravagant party, inviting everyone in their social circle. Jessica, running low on drugs and cash, rushes to Lionel to procure more Twelve, further entwining her fate with that of her peers. During a drug deal, Tobias encounters Molly and invites her to Sara’s gathering, causing Mike to intervene in an attempt to protect her from his chaotic world.
As chaos unfolds at the party, Claude isolates himself in his room, practicing with his weapons. Lionel confronts Jessica upon realizing she doesn’t have the expected payment, leading to a disturbing and desperate transaction. Mike receives devastating news about Charlie's death, prompting him to seek out Molly. However, distractingly caught up in the festivities, he inadvertently stumbles upon an alarming scene featuring Jessica and Lionel.
The situation escalates rapidly when Lionel brandishes a gun, ultimately igniting a horrifying chain reaction as Claude begins shooting into the crowd. Panic ensues, leading to the tragic demise of several teenagers, including Lionel himself, while Claude makes the fatal decision to confront the police, resulting in a suicide by cop.
In the aftermath, as Sara lies dying, her haunting reflection reveals the dark quest for fame amidst their lives of excess. Eventually, Mike awakens in the hospital, facing Molly's harsh words about his drug-dependent lifestyle. He longs to reconnect but is rebuffed. In a poignant moment of healing, Mike visits Nana’s mother, finding solace in their shared loss, and finally begins to reconcile with the pain from his mother’s passing.
