A new type of deadly virus spread throughout the city, and the apartment where has different social classes of people is sealed off. With the fear of the virus, and the conflicts of the different classes, the residents have to spend and survive in the new habitation. Yoon Sae Bom is very quick on decision and judgement. She did not grow up in a good environment. She wants to live comfortably in the complicated world, but she righteous and can’t stand injustice. Jung Yi Hyun is a police detective, who is mainly in charge of violent crimes. He used to be a baseball player, but had to quit due to a knee injury. He struggles to protect people from the danger in the apartment. Han Tae Seok was an information agent while serving in the military, and after being discharged, he worked as an executive at a pharmaceutical company. He is the perfect person for a position dealing with infectious diseases.