The disappearance of children from all over the metro area has caused a city-wide scare. Each child shared something in common—they were all diagnosed with rare and life-threatening illnesses. In a series of controlled experimentation, they were all infected with the new TA virus to test its effect on the human body and genetic makeup. One vile housed a contagion that mimicked a powerful and rare form of anemia that caused an intense thirst for blood in each patient. Nine year-old Seo Junghwa and eleven year-old Kim Jonghyun were among the group of patients. Their bodies had grown immune to the treatment, and they could no longer be controlled.

When the two manage to escape the facility, the government had to find a way to retrieve them without further spreading the toxin. After years of searching, the trail had gone cold. Detective-in-training Kim Kibum enters the field with high hopes of reopening the case. When a string of peculiar homicides occur all over the city, the young rookie is placed on the assignment. Along the way, Kibum encounters a man that is just as bizarre as he is charming. His business practices are beyond the norm, forcing the young detective to take a deeper look at the other's past. Nothing prepares him for the secrets that he unlocks during his search. When his job is put on the line, he must decide whether to disclose government information or stay true to himself.