"All Of Us Are Dead"|Season 1|Episode 4

Cheong-San's mother reaches the school, but is attacked by a zombified Gyeong-Su and devoured on the football field. After police detective Song Jae-ik arrests Byeong-chan and brings him into custody for creating the virus, Byeong-chan recounts that he was angered at the school's indifference towards the bullies who frequently abused his son. He created a virus in an attempt to make his son stronger, only to see his son develop into a zombie, and attacked his mother, who also turned. A zombie horde attacks the police station, and Byeong-chan is bitten. Using his final moments, Byeong-chan tells Jae-ik that his laptop is in the school's science lab with the answer to eradicate the virus and he stays behind to block the horde. After receiving the crucial information, Jae-ik and his sole surviving junior colleague Jeon Ho-chul escape the station. Meanwhile, Su-hyeok and Cheong-san attempt to retrieve a phone from the staff room and encounter Eun-Ji, a bullying victim of Gwi-Nam who was bitten but did not turn. The pair are separated by zombies. Su-hyeok returns alone to the broadcasting room with the phone. Cheong-san hides in the principal's room, where he witnesses Gwi-nam killing the principal. He flees, with Gwi-nam chasing him. In the outside world, after losing a teammate and a councilor, So-ju and his remaining teammate Kim Woo-shin evacuates the governmental survivors and board a helicopter.