Season 1

When young hotshot Han Ju-won arrives in town, he's assigned to partner with Lee Dong-sik, a maverick cop with a gruesome tragedy in his past.

The discovery of an unidentified human skeleton raises unsettling possibilities. Dong-sik drags Kang Min-jeong back to town from a Seoul night club.

Ju-won's suspicions about Dong-sik's involvement in the case intensify. The emergence of a mysterious cellphone places Ju-won in a tight spot.

Coming up empty with Dong-sik's interrogation, the police root around Yoo Jae-i's butcher shop. Ju-won makes an explosive statement to the public.

A fight breaks out as Dong-sik prevents Kang Jin-muk from being taken advantage of. Oh Ji-hun is confronted about the night of the disappearance.

Ju-won agrees to Jin-muk's request to carry out his own unofficial investigation. Do Hae-won moves to put an end to the case and protect her son.

Park Jeong-je does the right thing. The arrival of a second text from Min-jeong points Dong-sik toward someone who's figured out the truth.

News of the killer's arrest scandalizes the town. The killer refuses to speak to anyone but Dong-sik and Ju-won. Their interrogation hits a nerve.

Following a clue from an old video, Dong-sik searches desperately for his sister's remains. Ju-won and Jae-i each return after three months away.

Seeing CCTV footage, Dong-sik is convinced he's figured out the real culprit behind the killer's death. Ju-won puts a GPS tracker on Nam Sang-bae.

Committed to getting to the bottom of the latest murder, the team pulls together — and considers two of their own as prime suspects.

The truth behind the events from the night of Lee Yu-yeon's death begins to unravel. Jeong-je struggles to remember what happened.

As detectives begin to connect the dots, Han Ki-hwan's ties to the case become clearer. Dong-sik asks Ju-won if he can trust him.

Dong-sik listens in on a conversation that brings to light many long-held secrets. A determined Ju-won sets out to uncover further truths.

After obtaining an astonishing audio recording, Ju-won resolves to pursue justice at any cost. Dong-sik and Ju-won question Lee Chang-jin.

In the aftermath of another sudden killing, Dong-sik joins hands with Ju-won to bring down the guilty — and deliver necessary punishment.