During a fight with a zombie, Han Gyeong-su is scratched on the arm. Lee Na-yeon , driven by her prejudice against his social status (calling him a "welfie"), insists he is infected and demands the group kick him out.

In a parallel storyline, a student named Park Hee-su gives birth alone in a public bathroom and later sacrifices herself to protect her newborn baby from the surrounding zombies. Episode Details All of Us Are Dead – Season 1 Episode 3 Recap & Review

In the third episode of the K-drama (internationally known as All of Us Are Dead ), the tension between the students reaches a breaking point as the virus continues to spread both inside and outside the school. Plot Summary

Outside the school, the virus has completely overtaken the city of Hyosan. We see the detective Song Jae-ik learning about the virus's origins from the creator, Lee Byeong-chan, who is being held at the police station.

To prove she is "right," Na-yeon secretly rubs zombie blood from a handkerchief onto Gyeong-su's open wound. This leads to his actual infection and eventual transformation into a zombie, devastating his best friend Cheong-san.

After Nam-ra exposes Na-yeon's actions, the group turns on Na-yeon. Feeling isolated, she leaves the safety of the room. Their teacher, Ms. Park , follows her in an attempt to save her, leading to her own tragic fate.