It is a drama that depicts the process of a soldier, Jae Yun, and his girlfriend, Yeong Ju, who have just been notified of a breakout, fighting against hordes of zombies and running toward each other, set in an air defense unit in a high-rise building in Seoul. Jae Yun enlisted in the military at the late age of 26 while seeking alternative service through employment in the defense industry. Anxious about his future, he becomes obsessed with his girlfriend, eventually breaks up with her, and faces a world turned upside down by hordes of zombies. He was weak and lacked confidence, but as he fought the zombie outbreak, he gradually began to act as the leader of the squad. Yeong Ju is a rubber rookie who is new to society and is having a hard time with Jae Yun, who does not understand her feelings before being notified of their breakup. As she sets out to meet her boyfriend, she discovers a zombie outbreak and gradually becomes stronger in the fight for survival.