Description

A gang of bullies from Hyosan High School corner student Lee Jin-su on the rooftop of a building. As he tries to fight them off, Jin-su falls off the rooftop and is hospitalized. Lee Byeong-chan, Jin-su’s father and a science teacher in Hyosan High, visits his son and sees him transforming into a zombie. One of the bullies, Kim Hyeon-ju, is bitten at school by an infected hamster in the science lab. Upon seeing this, Byeong-chan locks Hyeon-ju inside the lab. She escapes the next day, having become severely ill, and collapses in Ms. Park’s class. Hyeon-ju is taken to the school clinic where she suddenly bites the school nurse, and is then rushed to the hospital. The virus begins to rapidly spread within the school after the infected nurse turns into a zombie and attacks several students.
Students and childhood best friends Nam On-jo and Lee Cheong-san flee the cafeteria and take refuge in class 2-5 with their surviving classmates, including class president Choi Nam-ra, former delinquent Lee Su-hyeok, Cheong-san’s best friend Han Gyeong-su, On-Jo’s best friend Yoon I-sak, entitled rich girl Lee Na-yeon, book-smart Oh Joon-yeong, as well as Kim Ji-min, Seo Hyo-ryung, Yang Dae-su, Jang Woo-jin, and Kim Min-ji. An infected teacher enters the classroom, turns into a zombie, and bites Min-ji, forcing the group to flee into another classroom. I-sak is bitten in the process and is thrown out the window when she turns. The students use a fire hose to climb down to the broadcasting room, where Ms. Park is hiding. Meanwhile, Yoon Gwi-nam, one of the school’s bullies, hides in the cafeteria’s kitchen with two students and a lunch lady. Jang Ha-ri, Woo-jin’s sister, and Jung Min-jae arrive with the school’s archery team and rescue senior students Yoo Jun-seong and Park Mi-jin in the restroom from an infected student. At the hospital, an infected Hyeon-ju bites several others, causing the virus to rapidly spread throughout Hyosan.
In the broadcasting room, a zombie attacks the group through the window; Gyeong-su is scratched in the struggle. Na-yeon accuses him of being infected and Gyeong-su isolates himself for their safety. When the others reproach her, Na-yeon pretends to apologize to Gyeong-su, secretly smearing zombie blood on a handkerchief and applying it to his wound. Gyeong-su turns into a zombie, forcing the group to throw him out the window. Nam-ra reveals Na-yeon’s actions and the group condemns her for Gyeong-su’s death. Frustrated, Na-yeon leaves, followed by a concerned Ms. Park. Gwi-nam escapes the cafeteria alone after pushing the others into the zombies. Meanwhile, the citywide outbreak prompts government forces – led by Commander Jin Seon-moo – to declare martial law as they begin evacuating survivors. Cheong-san’s mother heads towards the school in search of her son. Firefighter and On-jo’s father, Nam So-ju, is trapped with his crew, assemblywoman Park Eun-hee, and other government officials inside a government building. Elsewhere, student Park Hee-su gives birth in a public bathroom stall and flees with the baby as zombies overrun Hyosan. She is bitten, however, and takes refuge inside Cheong-san’s family restaurant. She leaves the baby out of her reach and ties herself to the front door before succumbing to the infection.
Cheong-san’s arrives at the school, only to be quickly swarmed and killed by a horde of zombies, among them a zombified Gyeong-su. Police detective Song Jae-ik interrogates Byeong-chan, who confesses to creating the virus (which he named the “Jonas Virus”) in an attempt to strengthen Jin-su, arguing that the school did not do enough to help him. However, Jin-su’s condition worsened and became a zombie instead. His body is smuggled home by Byeong-chan; Jin-su bit his mother, resulting in her infection as well. Byeong-chan has since tried to find a cure, to no success. A zombie horde suddenly swarms the police station. Byeong-chan is bitten and tells Jae-ik that the solution to the virus is on his laptop in Hyosan High’s science lab. He sacrifices himself into the horde, allowing Jae-ik and junior police officer Jeon Ho-chul to escape. Meanwhile, Su-hyeok and Cheong-san retrieve a smartphone from the staff room and encounter Eun-Ji, a bullying victim of Gwi-Nam who was bitten but did not turn. The two are separated by zombies, and Su-hyeok manages to safely return to the broadcasting room. Cheong-san flees with the phone and momentarily takes refuge in the principal’s office, where he witnesses Gwi-nam killing the principal. He flees again with Gwi-nam in pursuit. So-ju and a surviving crewmate manage to safely escort the remaining members of the Hyosan government to a helicopter, which they board for evacuation.