It started like any other day at Hyosan High School, the day everything went to hell. As Class 2-5 takes part in their regular morning proceedings, they are disrupted by the sudden emergence of student Kim Hyeonju. The withered and worn-out girl claims that science teacher Lee Byeongchan had kept her prisoner for days after she was bitten by his rabid lab hamsters. The police are quickly called, Mr. Lee is detained, and Hyeonju is taken to the city hospital—though not before she bites another student in her worsening condition. In no time, Hyeonju's behavior spreads rapidly throughout the school; more students become rabid and start viciously attacking the non-infected. As the students of Class 2-5 attempt to escape the confusion, they must contend with the deteriorating situation and find a way to survive in their school, where their closest friends are now hell-bent on killing them. [Written by MAL Rewrite]