Season 1

After his superior is arrested, Kang Tae-ju is reassigned and returns to his hometown of Kangseong following a demotion. On his first day working at the local office, he learns from his coworkers that a former convict connected to one of his past cases has been brutally assaulted.

Following a tense and uneasy reunion with Si-young, Tae-ju throws himself back into the hunt for the serial killer. As the investigation intensifies, a determined reporter named Ji-won becomes involved, joining the effort to track down the murderer.

After Tae-ju assaults the county governor's nephew in retaliation for Soon-young's attack, he faces the serious threat of losing his position. Meanwhile, a victim's testimony leads him to a troubling discovery

Reeling from the death of Min-ji, who had placed her trust in him, Tae-ju seeks out Si-young and proposes that they work together to capture the serial killer. His return sparks tension and debate among his colleagues, but Tae-ju remains single-minded, determined to continue the hunt.

As suspicion tightens around Gi-beom, evidence seems to seal his guilt. However, more evidence proves to contradict the timeline. As Tae-ju digs deeper, suspicion shifts toward someone with close access.

Doubt grows over Lee Gi-beom's guilt as his confession is exposed as coerced through illegal detention and abuse. Tae-ju confronts corruption within the investigation while Ji-won uncovers new leads.

Doubts grow over Lee Gi-beom's confession as Tae-ju uncovers corruption, illegal detention, and a cover-up. Suspicion shifts to Im Seok-man, while new evidence reignites the hunt for the real serial killer.

Im Seok-man is forced into a false confession during a police reenactment, while authorities declare the case solved. Tae-ju grows suspicious and starts uncovering corruption behind the investigation and Gi-beom's death.

As buried secrets resurface, Tae-ju begins uncovering a terrifying truth behind the serial killer case everyone believed was solved. A hidden child, suspicious police involvement, and growing distrust push the investigation into darker territory, forcing the team to question everything they thought they knew.

Tae-ju gets closer to exposing the truth as shocking connections between past victims and the police begin to surface. Trust inside the team starts to crack, while a dangerous suspect makes a bold move that puts everyone at risk. With time running out, the investigation spirals toward an explosive confrontation.

A tragic accident pushes Tae-ju to make a desperate choice as hidden family ties and painful secrets resurface. While Soonyoung fights for her life, old wounds, guilt, and power struggles threaten to destroy everyone connected to the past.

In the emotional finale, long-buried truths finally come to light as Tae-ju and Soon-young face the consequences of the past. With betrayal, sacrifice, and grief reaching their peak, the final confrontation forces everyone to choose between revenge and forgiveness - leading to a heartbreaking but unforgettable ending.