Kang Tae Joo comes back to his hometown, Kangseong, as a result of a demotion because of the arrest of his chief. 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.

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.

After Tae Joo used violence against the county governor’s nephew because Sun Yeong was assaulted by him, he is in danger of being resigned. Through the testimony from a victim, he realizes that there is another victim of the serial murder case among the missing people. So he promises that he will find the body of the new victim with the condition of his resignation.

After the death of Min Ji, who showed trust in Tae Joo, Tae Joo meets Si Yeong and suggests catching the serial killer together. Tae Joo’s comeback arouses controversy among his colleagues, but he just focuses on tracking the killer. And he discovers a connection between Min Ji and Gi Beom.

As suspicion toward Gi Beom grows, Tae Joo is confused because the circumstances point to Gi Beom as the killer, but he hesitates to arrest him for some reason. After another murder case happens, he tries to find the missing Gi Beom to ask about everything, being sure that Gi Beom is the killer. Si Yeong, who was attacked by the killer, wakes up, and he reconciles with Tae Joo.

Gi Beom is continuously confined, tortured, and threatened, forced into giving a false confession by Si Yeong and his subordinate detectives. Using a handbag found as evidence, Ji Won begins to deduce the real culprit and eventually tracks down a suspicious man, attempting to interview him.

Despite Si Yeong's interference, Tae Joo continues the investigation and realises that all the clues are pointing toward Seok Man. Late at night, Seok Man visits Sun Yeong to return her handkerchief, and she begins to suspect him. Meanwhile, Gi Beom is cleared of suspicion and released. However, on his way home, he is met with another tragedy.

Corrupt detectives continue to torture Seok Man, forcing him to give a false confession. Tae Joo is instead framed as the officer who illegally assaulted Gi Beom, leading to his death, and finds himself on the brink of demotion. Ji Won attempts to write an article to help Tae Joo but runs into serious obstacles. Meanwhile, Sun Yeong suddenly goes missing, and Tae Joo along with the entire village searches desperately for her.

Right before Seok Man is in danger of being sentenced to the death penalty, a doctor who led the autopsies of the murder case changes the atmosphere of the court, insisting that Seok Man isn’t the killer. Meanwhile, Tae Joo comes back to the Kangseong and declares that the serial murder case is not over yet. And Tae Joo digs into the case of a missing child, which seems like the evidence of the killer's new activity.

After Dae Ho tells Tae Joo about the conspiracy on Hye Jin's body, Tae Joo goes on another secret plan to get a hint from Si Yeong about where she is. But things go even more complicated because Si Yeong turns out to be Sun Yeong’s half-sibling. With a frustrating feeling about the relationship of Si Yeong and Sun Yeong, Tae Joo rushes to find Hye Jin’s body.

Based on the confession of the murderer, Tae Joo visits Seok Man’s house and begs for his forgiveness for making him the culprit. He decides to do the retrial for Seok Man’s innocence, and meets his past colleagues to persuade them to tell the world the truth about Hye Jin’s missing body. Meanwhile, Yeong Beom, the son of Sun Yeong, becomes a reporter, investigates the Kangseong Serial Murders, and meets Tae Joo, unaware of their relationship.

Despite Yeong Beom’s blame to Tae Joo, Tae Joo gives all of his heart and strength for Seok Man’s retrial and Hye Jin’s case steadily. He even stars on Ji Won’s news and reveals the culprit of Hye Jin’s case openly. Through the news, the situation goes chaotic. Shocked, Yeong Beom and Sun Yeong go to Si Yeong’s office, and they blame him. But Yeong Beom requests Si Yeong to say the truth in the court as a last chance. Will Si Yeong say the truth? And will Seok Man’s honor be restored?