The film kicks off with Simon (Tyron Leitso) and Greg (Will Sanderson) making plans for a boat ride to an epic island rave party. They soon meet up with friends Alicia (Ona Grauer), Karma (Enuka Okuma), and Cynthia (Sonya Salomaa). Unbeknownst to them, while Karma has her sights set on Simon, he is infatuated with Alicia, and Cynthia is in a relationship with Greg.Upon reaching the dock, they discover that the boat to the island has already departed, prompting them to catch a lift with Victor Kirk (Jürgen Prochnow) and his sidekick Salish (Clint Howard). Just as they set off, a cop named Jordan Casper (Ellie Cornell) tries to prevent their departure, warning them of Kirk's smuggling activities, but they manage to leave anyway.
Upon arrival at the party location, they find it chaos and eerily deserted. Alicia, Karma, and Simon venture off to locate their friends, leaving Cynthia and Greg behind. The couple shares a passionate moment in a tent, but Greg steps out briefly, leaving Cynthia vulnerable to a surprise attack from a horde of zombies. Meanwhile, the others find refuge in an old house, where they encounter three survivors: Rudy (Jonathan Cherry), Liberty (Kira Clavell), and Hugh (Michael Eklund). These survivors inform them of the zombie invasion that wiped out the rave attendees. The group hastily returns to the rave site in search of other survivors, but Salish meets a grim fate while wandering through the woods.
The gang regroups at the rave site, only to be confronted by a transformed Cynthia, now a zombie. She attacks and kills Hugh before Jordan Casper intervenes and shoots her. The remaining friends formulate a plan to escape the island using Kirk's boat, but soon discover that it has been overtaken by zombies. Desperate, Casper and Greg head off to search for help, but their attempt ends in tragedy when Greg falls victim to a sudden zombie ambush.
Kirk, in a bid to protect the teens, reveals a stash of weapons he has been smuggling. Armed and determined, the group heads back to the house, only to find it besieged by zombies, leading to an intense and chaotic gunfight that feels reminiscent of a video game. Unfortunately, Liberty and Casper fall during the onslaught, while the few survivors manage to reach safety inside the house.
Kirk is lured outside by the sound of Salish whistling, only to discover him transformed into a zombie. In a heart-stopping moment, Salish bites Kirk before being shot dead. With the zombies breaking in, Kirk makes the ultimate sacrifice by detonating explosives, allowing the undead to swarm the house. The remaining four teens barricade themselves inside a lab, but the zombies breach their defenses. In a moment of heroism, Karma discovers a hatch in the floor, prompting her, Alicia, and Rudy to descend into the tunnels below. As Simon bravely covers their escape, he triggers an explosion that destroys the house, taking down a horde of zombies in the process.
In the tunnels, Karma courageously sacrifices herself to save Alicia and Rudy from the advancing zombies. However, not long after, they are captured by a man named Castillo, who, after injecting himself with an immortality serum decades ago, unintentionally birthed the first zombie. As chaos ensues, Alicia and Rudy struggle for their lives, desperately trying to escape while igniting further destruction behind them. Alicia, engaged in a fierce duel with Castillo, ultimately meets a tragic fate as he stabs her in the heart. Rudy, in a moment of instinct, decapitates Castillo, believing the fight is over, but discovers that Castillo's headless body still poses a deadly threat. Alicia, with her last ounce of strength, crushes Castillo's head, finally vanquishing him, but collapses soon after.
In the climactic finale, Rudy and Alicia are rescued by a squad of federal agents arriving to eliminate the remaining zombies. As the dust settles, a haunting narration reveals that Rudy has given Alicia the immortality serum, leaving her in a state where she may eventually succumb to the curse of being a zombie, ensuring the cycle of horror continues.
