Episodes
1. Episode 1Inside Lee Byeong-chan's science lab, a student incurs a seemingly harmless bite. Shortly after, a fast-spreading outbreak soaks the school in blood.
2. Episode 2The infected multiply in droves. Scrambling for their lives, Nam On-jo and Lee Cheong-san find safety with others inside a classroom — but not for long.
3. Episode 3When one of the group is scratched while fighting a zombie, Lee Na-yeon demands they kick him out. Outside, the virus swallows up the city.
4. Episode 4In need of a cellphone, two students take a risky journey to the teachers' office. Byeong-chan passes on critical information to Detective Song Jae-ik.
5. Episode 5Martial law is imposed on the city. When Cheong-san is separated from the rest of the group, On-jo leads a mission to use a drone to locate him.
6. Episode 6The group clears a path to Cheong-san using sound to draw away zombies, but a new type of threat surfaces. Nam So-ju breaks out of the quarantine camp.
7. Episode 7To make it out of the music room and onto the roof, the students put into action their most perilous plan yet. Elsewhere, Jae-ik comes across a setback.
8. Episode 8Jae-ik and his crew run into a student from the school. Na-yeon works up the courage to face her peers. The group shares confessions around a fire.
9. Episode 9A disturbance at the camp shifts the military's understanding of the virus. A thunderstorm provides cover as the group agrees to keep on moving.
10. Episode 10The auditorium quickly becomes a trap for the two newly united teams of survivors. Byeong-chan's video logs reveal a drastic solution to the crisis.
11. Episode 11Though a surprise protector provides the group safe passage to their next stop, Yoon Gwi-nam is not far behind. The military makes a grave decision.
12. Episode 12The students make it to the quarantine camp, each of them weighed down by tragic loss. Months later, they hang on to hope for a survivor.
