At night, two men are seen near a cave; one, a detective named Mr. Miller, is beaten and restrained. The other man, filled with rage, interrogates him. When the questioning yields no results, he activates a device attached to Miller's vest. In the present, a group of former high school friends reunites for a camping trip. The ensemble includes valedictorian [Rian](reine-swart) and her boyfriend [PJ](cameron-scott), a rock drummer; popular [Ezra](steven-john-ward), reserved [Erin](liesl-ahlers), the couple [Shea](suraya-rose-santos) and [Bobby](michael-lawrence-potter), best friends [Amber](paige-bonnin) and [Cici](kayla-privett), along with the brooding [Kato](russell-crous). As the night unfolds, a mysterious figure releases gas that renders the friends unconscious.
When they awaken, the friends discover they are strapped to suicide bomb vests. The perpetrator, [Mr. Peterson](sean-cameron-michael), a former science teacher, holds them at gunpoint, blaming them for his son Caleb's death from a drug overdose at a party they hosted. The tragedy shattered his family, culminating in his wife's overdose. He sets timers on each vest, declaring that only one among them may survive, before tragically taking his own life.
As panic ensues, a battered Bobby is found, and he reveals that he had aided Mr. Peterson, having been blackmailed about his bisexuality back in high school. His attempt to kill Kato fails and leads to his own demise as the vest explodes. Following Bobby's death, PJ is next in line for the lowest timer. In a tragic mishap, he accidentally kills Shea, which leads to the horrible realization that her time is now added to his vest.
Rian uncovers the dark truth behind the timers, only to find that they will need to turn on each other to survive. Cici, overhearing their desperate conversation, spirals into madness and goes on the attack. A confrontation escalates, resulting in Amber tragically killing her best friend, Cici. Kato persuades Amber to ally with him, targeting the remaining group for survival.
Meanwhile, [Ezra](steven-john-ward) partners with [Erin](liesl-ahlers) and they encounter the bloodied and bound Detective Miller, who reveals that Peterson had forced him to reopen Caleb's case under threats. He uncovers that Caleb’s overdose was not an accident but a calculated act of foul play. As Miller is mortally injured, Ezra makes a selfless decision, sacrificing himself so that Erin may gain his time. He confronts Kato, believing him to be responsible for Caleb's death, leading to a fierce struggle.
As chaos reigns, Kato shoots PJ and brutally turns on Amber after discovering her betrayal. Rian, in a bid to save herself, finds a second remote intended to disable the vests. However, Peterson has set a trap, resetting the timers in a cruel twist. Struggling with guilt, Rian confesses to being responsible for Caleb's overdose, revealing her desperate actions to secure her academic future. In a sudden strike, Kato kills Rian, leaving Erin to inherit her timer.
Now emboldened, Erin shoots Kato and manages to outmaneuver him. Kato attempts suicide as time runs out, but he fails and meets his explosive end. Erin's vest displays a taunting message: "All your friends are dead! Have a nice life!" Before it deactivates, letting her free from the vest, she is left grieving the loss of all her friends.
In a chilling post-credit scene, Erin finds her way to a road and flags down a passing vehicle. However, when the driver notices her gun, he flees. Her scream resonates into the night, but slowly, a smile creeps across her face.
