An unidentified epidemic with a 100% fatality rate strikes Seoul. There is no guarantee who will be alive tomorrow. The Korea Center for Disease Control (KCDC) begins investigating the unknown so-called “M(Moon)” Virus. The KCDC tracks the origin of the “M” virus, uncovering that the carrier is, in fact, an ordinary student. Realizing he has the virus, the carrier student secretly runs off. Finding the fugitive becomes a top priority for theKCDC’s virus investigators. Joo Heon is the KCDC’s Sherlock Holmes with his sharp instincts. While the investigation is underway, Joo Heon gradually becomes infatuated with Na Hyun, his fellow investigator. After much hesitation, he eventually confesses his feelings for her. When they share their feelings, the M virus puts their romance in jeopardy, when Na Hyun is infected with the virus.
~~ Adapted from the novel “Infectious Disease” by Bae Young Ik.