Young-joo, who is focused on adjusting to her new job, grows tired of the constant complaints of her boyfriend, Jae-yoon, who's serving in the anti-aircraft unit at 77 A Tower. She breaks up with Jae-yoon, and he accepts the breakup with a heartfelt voice message. Upon hearing this, Young-joo heads to the tower to meet Jae-yoon, but on her way there, she encounters an unexpected incident.

Jae-yoon and his direct junior, In-ho, head down to Eden Hotel, right below their air defense unit, for an errand. Upon arrival, they find a plane crashing into the heart of Seoul, and the hotel turned into a bloody chaos. Meanwhile, Young-joo and Jin-wook also confront zombies and team up with Tae-shik, who happens to be passing by. Together, they begin their fight for survival.