Contains spoilers for this episode and earlier episodes.
Su-hyeok helps Cheong-san cling to the fire hose and reach the broadcasting room alive. Their reunion gives the classmates a moment to search for news, but an infected student reaches the window and attacks. Gyeong-su helps drive it away and suffers a scratch. Na-yeon insists that he is infected, mixing her fear with the contempt she already holds for his family's poverty. Sun-hwa separates him in the recording room while the others wait for symptoms.
The infection is spreading through Hyosan as police barricades fail and families try to reach the school. Cheong-san's mother sets out to find him, while Hee-su gives birth alone in a public bathroom. She returns for her baby as the streets become dangerous. After being bitten, she shelters in a restaurant and ties herself near the door, keeping her body away from the newborn before she loses control of her actions.
Na-yeon goes into the recording room under pressure to apologize. She wipes Gyeong-su's scratch with a handkerchief carrying infected blood, deliberately causing the change she claimed to fear. When he turns, Cheong-san whistles to draw his friend toward the window. Nam-ra reveals what she saw Na-yeon do, and the others confront her. Na-yeon leaves the room alone; Sun-hwa follows to save her after warning the students against taking another life. A helicopter's light reaches the remaining classmates.