An unknown fire incident happens, and soon a lethal virus spreads across Korea. The special virus disease control team starts to strace the virus, and Jeong Ujin starts his investigation.

The disease control center traces the identity of the virus carriers. Meanwhile, Myeongheon realizes that his ex wife is infected by the virus.

The disease control team learns that someone is helping Kim Incheol escape intentionally. Soon, Myeonghyeon's mask comes off during a fight with Incheol, hence he goes into quarantine.

Incheol fears his symptoms and comes to see Myeonghyeon, but soon they get involved in a car crash. However, nobody wants to carry out Incheol's surgery, hence Myeonghyeon does it himself.

Incheol gets kidnapped by strangers, and Myeonghyeon goes after the kidnapper. Meanwhile, Myeonghyeon suspects and arrests Chief Yun for going into Incheol's hospital room when nobody is around.

Myeonghyeon is disappointed at the fact that it is difficult to make the virus cure due to Incheol and Chief Yun's deaths. Meanwhile, Myeonghyeon gets suspected of murder unexpectedly.