Residents of Gangsan Mansion tremble in fear when a female high school student in the neighborhood is murdered. When the corpse is found, the residents become suspicious of KANG Seung-hyuck, the serial killer who also resides in Gangsan Mansion. The bag store owner is suspicious of KANG because the suitcase used in the crime matches the suitcase he sold to KANG, and the pizza delivery man believes KANG is the suspect because the time when KANG ordered pizza matches the time when the victim was reported missing. The security guard also senses that KANG is involved in the missing case of a security guard. When KANG plots to kidnap another girl in the neighborhood and abducts the bag store owner, the neighbors finally decide to take action and prepare for a counterattack.