The residents in Building 101 suspect Sae Bom and Yi Hyun are infected and quarantine them in their unit. With them quarantined, the residents discuss what to do about them. Making matters worse is the dwindling food and water supply. If they can't get it from outside, the only choice is to take it from someone else. Meanwhile, Sae Bom and Yi Hyun figure out how to find out who is infected.
Elenco: Han Hyo-joo , Park Hyung-sik , Jo Woo-jin , Park Joo-hee , Lee Ji-ha , Bek Hyun-jin , Park Hyung-Soo , Han Da-sol , Park Hee-von , Moon Ye-won , Kim Young-woong , Na Chul , Cha Soon-bae , Lee Ju-seung , Han Jun-woo , Yoo Ji-yeon , Bae Hae-sun , Kang Han-saem .