Kang Tae Joo returns to his hometown, Kangseong, after being demoted following his chief's arrest. On the first day at the Kangseong office, he finds out from his colleagues that an ex-convict from his past case has been beaten. Although he believes he is not the culprit, the situation doesn’t go as he thinks. While investigating the case, he meets his classmate, Cha Si Yeong, who has bullied him badly. Si Yeong greets Tae Joo with a smile, but it seems Tae Joo hasn’t moved on from the memory.
After an uncomfortable reunion with Si Yeong, Tae Joo resumes tracking the serial killer. Ji Won, a female reporter, also joins the operation to catch the murderer. Meanwhile, Gi Beom proposes to Sun Yeong, but soon grows uneasy after seeing her leave work in her male colleague’s car. At the same time, Tae Joo, dispatched to a college student protest, spots a male student who resembles Gi Beom and begins to grow suspicious.
