Episodes 1–3: Jae-yoon breaks up with Young-ju over the phone due to military anxiety. A zombie virus breaks out in Seoul, trapping Jae-yoon on Tower 77A while Young-ju sets out across Gangnam to find him.
Episodes 4–5: Flashbacks reveal Young-ju pursued Jae-yoon first during college. Survivors discover that alcohol slows down or temporarily stalls the viral transformation.
Episode 6: A stampede in a Seoul subway station leads to the death of Young-ju’s senior Jin-wook. Jae-yoon’s squad commander is infected and executed by his sergeant.
Episode 7: The sergeant is infected and requests his stepson to execute him before turning. Jae-yoon escapes a window fall using a giant teddy bear suit.
Episode 8 Finale: Jae-yoon’s squad fights through Tower A. Squad Leader Kim Yeong-man stays behind as he turns, ordering his men to survive. Jae-yoon rescues Young-ju from hostiles. Young-ju later learns that Park Eun-chae, the station worker who led her to safety, had actually been dead for 10 hours—revealing a supernatural guardian element before the couple escapes into the city.