High school student Kelly, Steffi, and her boyfriend Gary are camping out at night when tragedy strikes: an unseen assailant stabs Gary to death and impales Kelly with a hiking stick, forcing a brutal beginning to a nightmare that will engulf Bridgemont High.
The next day, the Bridgemont High cheerleading squad — Parker Jameson as Parker, Angela Caruso as Angela, Tammy Rae as Tammy, Shelley as Shelley, and Dina as Dina — gather for practice before heading out to a distant event. In the locker room, Shelley mourns a former teammate, Marissa, who died exactly a year earlier. As the group finishes, Dina heads back inside to retrieve her purse and is killed, leaving the remaining students stunned. They depart in a van with their coach, Ms. Hendricks, their driver Buzzy, and two other students, Mark and Ryan, believing Dina was already on the bus.
In nearby town, Sheriff Frank Murdock and Deputy Adams GiGi Erneta are alerted by the Fresno Police chief that Jeremiah MacPherson, a serial killer who escaped from a mental hospital the day before, may be moving toward their area. A jogger named Debbie is killed when someone cuts the ropes of a suspension bridge she’s crossing, adding to the growing fear. Murdock and Adams start chasing leads on Kelly and Gary’s murders, while they also visit retired Sheriff Monty Coltrain to warn him about the escape. There, they learn that Dina has turned up gutted at the high school, a crime that doesn’t fit MacPherson’s usual MO. When Officers Phillips and Kimble spot a jacket near the road and stop to investigate, MacPherson ambushes them, killing both and stealing their squad car. The investigation then towns in on MacPherson after Adams and Murdock visit Linda, one of MacPherson’s surviving victims, hoping her memory might yield more clues. In a flashback, he attacks Linda in the high school with a large power drill, leaving her for dead.
As the snow deepens, the cheerleaders encounter a roadblock and must detour through a snowy mountain pass. Their van runs dry in the worsening storm, and they take refuge in a deserted vacation cabin. Meanwhile, Melissa DeMarco, the Fresno Police chief’s assistant, calls to warn that MacPherson left a voicemail using Debbie’s cell phone, hinting that he is not working alone. Deputy Adams learns the missing squad has not been found, and she and Sheriff Murdock set out to search for them.
MacPherson arrives at Monty’s cabin in the stolen squad car. Gunfire erupts as the two exchange shots and MacPherson bolts into the woods. Buzzy steps outside to investigate the gunfire but is distracted when he spots Tammy and Ryan having sex through a bedroom window, and the killer quietly strikes him with an axe. Mark goes outside to look for Buzzy and is decapitated, shocking the others. They scramble for a weapon, while Ryan and Angela attempt to seek help but become separated; Ryan is then strangled. Inside, Tammy, Shelley, and Ms. Hendricks regroup to address a failing fuse box. Shelley’s search leads her to the box, and she is electrocuted on contact. Tammy is dragged into a crawlspace and repeatedly stabbed. As MacPherson tracks him, Monty stumbles upon Shelley’s body, and Ms. Hendricks and Parker ambush Monty, knocking him unconscious and insisting he’s the killer. Angela arrives just in time to confront them at gunpoint, revealing a shocking truth: she killed the cheerleading squad to avenge Marissa’s death. Yet the real confession begins to come to light as Parker reveals a deeper conspiracy: the girls had slipped ecstasy into Marissa’s drink at a party, filmed her making out with Angela, and kept silent about it to protect one another. They didn’t want the truth to emerge.
In a climactic turn, Ms. Hendricks and Parker turn on the gas and hurl a Molotov cocktail into the cabin as Angela enters, blowing it up and killing her. The next morning, Deputy Adams stands with Monty outside Monty’s house, as Sheriff Murdock arranges to send Monty to the ambulance. In a final twist of fate, the ambulance’s driver is MacPherson, leaving the door open for a possible continuation of the nightmare.
