Plot

A group of high school students whose school bus crashes on a field trip. Relationships are tested once they realize they are being stalked by an attacker who intends to drive them out and straight into a horrifying fight to survive.

Evanston Hill High School teacher Mr. Lorenzo supervises as students board a bus for a field trip. Ever, an average girl with low self-esteem, boards with her best friend Tamra. Other students include Randall and Steven, two bullied loners who harbor crushes on Tamra and Ever; Danny, a jock; Hunt, Danny's best friend; Jacey, Danny's girlfriend; overweight outcast Ryan; and nerdy girl Candice. A sudden burst of blood on the windshield causes the driver, Wayne, to crash the bus in a forest. An emergency radio broadcast warns of a nearby chemical attack. A metalhead who appears to be a mutated zombie, later revealed to be a vengeful burnout named Chip, enters the bus and savagely mauls Lorenzo. In the ensuing commotion, Ever, Tamra, Randall, Steven, Danny, Hunt, and Jacey escape into the woods and seek safety in an abandoned building. Ryan joins them later. Meanwhile, Chip attacks Candice and others back on the bus.

Ever attempts to help Candice when she tries to join everyone in the building, but the other students deem rescuing her too risky, so they let Chip attack Candice again. Wayne, having seemingly mutated into a zombie like Chip, attacks everyone inside. Classmates who were also apparently transformed capture Hunt. Ever, Tamra, Randall, Steven, Danny, Jacey, and Ryan regroup in a room where they find mannequins dressed to resemble them, realizing someone has specifically targeted all of them. Wayne suddenly attacks again, but Randall beats him. Danny begins transforming after being stabbed with something during the commotion. Wayne rises to tackle Danny through a window onto the ground outside. Initially appearing dead, Danny surprisingly contorts and runs off.

Ever leaves Tamra behind after they argue about Tamra ignoring their friendship in favor of aligning with the "jocks". Ever and Steven return to the bus to look for a phone, although Ever becomes distracted by the radio, discovering that the emergency broadcast was actually a tape recording. Steven apologetically injects Ever from behind with a syringe. Before passing out, Ever sees Randall join Steven. A flashback shows that weeks earlier, Randall enlisted Steven for a scheme modeled after "Scared Straight!" where they would stage a zombie attack to get revenge on their bullies while looking like heroes to Tamra and Ever. Wayne volunteers, while ex-con and former student, Chip creates a dangerous drug to make people behave like zombies. Back in the present, Randall brings Steven back to the building to check on the students they injected and took captive, including Danny and Hunt. Meanwhile, Ever gathers enough strength to use a boom box to beat Chip.

Tamra finds Randall, who lies that zombies killed Ever. After Steven secretly injects the captive students with more of Chip's drug, Randall arms Tamra, Ryan, and Jacey with weapons as he rallies them to kill their supposedly transformed classmates. Ever suddenly interrupts to tell everyone the truth about Randall and Steven's plot. Tamra hits Randall, who inadvertently reveals a vanity mural he previously painted that depicts him and Steven as mythic heroes saving Tamra and Ever from zombified bullies. With the secret now fully exposed, Ever's allies rescue Danny and lock Steven in a cage with Hunt and the other ravenous "zombies". Everyone then fights with Randall, who gravely wounds Danny, as Ever uses a makeshift Freddy Krueger glove, that Chip created, to stab Randall with several syringes of the drug. Randall reforms as a "zombie". Tamra, Jacey, Candice, and another rescued young woman team up to take Randall down, with Ever finishing him off.

Hours later, Wayne, Chip, Randall, and Steven are all taken captive. The bullies and outcasts bond, with Ever and Tamra reconciling. After everyone boards the bus to leave, they discover Mr. Lorenzo is still alive.

Weeks later, PTA worker Ms. Operative visits Randall and Steven in prison, explaining that the PTA is bringing back the "Scared Straight" program, and invites them to be the masterminds. (thanks to Wikipedia)