Cha Hyun-su moves into the run-down Green Home by himself. Not long after, he witnesses a disturbing sight in his neighbor's apartment.

As a state of emergency is declared, the residents tie up Pyeon Sang-wook for being bitten. Hyun-su is unable to ignore a family in distress.

An unexpected savior protects the children from harm as Hyun-su, together with Yoon Ji-su and Jung Jae-heon, tries to bring them to safety.

Critical information about the monsters is made public. When residents are split on what to do with Hyun-su, Lee Eun-hyeok suggests they hold a vote.

Tasked to carry out dangerous missions, Hyun-su heads back to retrieve Han Du-sik. Sang-wook stops at nothing to finish what he started.