Stranger

As a teen, prosecutor Hwang Si-mok received surgical treatment for his abnormally developed brain, but the procedure left behind serious side effects.

The convict's strong plea for his innocence prompts Si-mok to review the CCTV clip. At the Yongsan police station, he runs into officer Han Yeo-jin.

Si-mok volunteers to appear on live national TV to discuss Kang Jin-seob. He also makes a bold promise to find the culprit within two months.

Rumors quickly spread about Si-mok's violent nature. Regardless, he persists in his investigation. He finds his mentee, Young Eun-su, suspicious.

Si-mok, puzzled by the details of the most recent murder case, visits the victim's home to seek more clues. Yeo-jin joins him in the investigation.

New pieces of evidence only increase the list of possible suspects. In the midst of the confusion, a few begin to question Si-mok's innocence.

Si-mok and Yeo-jin team up to covertly pursue Seo Dong-jae. Just as Dong-jae is about to throw something into the Han River, Yeo-jin stops him.

Enraged by what the police did to Park Kyung-wan, Yeo-jin tries to confront her superior but is stopped by Si-mok, who warns her of the consequences.

Si-mok selects key lawyers and police officers to be part of the special investigations team. Their probe begins with Dong-jae as the starting point.

Fearing for Ga-young's safety, Yeo-jin proceeds to transfer her to a different hospital. A nurse informs Yeo-jin of something strange that happened.

The truth behind Ga-young's convulsions is revealed. Chang-jun's wife receives a travel ban. Woo-gyun asks Chang-jun to help him get out of his mess.

Si-mok and Yeo-jin discover perplexing leads while searching Kyung-wan's basement. Dong-jae goes back to Chang-jun's office to fetch his cell phone.

Returning home from the rooftop party, Si-mok discovers that an intruder has left something in his bedroom. Yeo-jin and Geon come over right away.

Yeo-jin suspects a new killer is involved in the latest murder incident. Meanwhile, Si-mok collapses after leaving the autopsy.

Yeo-jin collects evidence as Si-mok interrogates the suspect. Many questions get answered, but the most important problem of all remains to be solved.

Si-mok sets out to meet the one he believes is the real murderer. He gets his hands on a bag that will determine the futures of many people.

On a foggy night, two college students drown at the beach. While Si-mok investigates, Yeo-jin tracks down a man who was at the scene of the incident.

Police and prosecutors each prepare members for joint discussions on investigative authority. Dong-jae brings Woo Tae-ha some cases of interest.

Yeo-jin recruits Geon. Digging into a policeman's death ruled as suicide, Si-mok and Dong-jae find signs that point toward a different story.

In a heated first session with prosecutors, Geon makes a pointed argument. At Hanjo, Lee Yeon-jae faces an oncoming family power struggle.

At the prison to interrogate an inmate, Yeo-jin runs into Si-mok and Dong-jae. Choi Bit has Yeo-jin deliver a mysterious file to an assemblyman.

Si-mok is ordered to find out what Yeo-jin knows about Bit's file. Ahead of a vote on the fate of her seat, Yeon-jae sets up an important meeting.

When Si-mok hears who’s gone missing, he starts gathering clues by going through phone records. Yeo-jin begins her own investigation.

Leading police efforts to locate Dong-jae, Yeo-jin connects the case to that of the dead policeman. Si-mok pays Yeon-jae a visit.

A perplexing photo containing a disturbing message surfaces. The police consider the possibility of the culprit being one of their own.

Si-mok turns his attention to an unusual case involving the sudden death of a former prosecutor, and finds that nothing quite adds up.

A witness, who says he saw the kidnapping, steps forward to identify the perpetrator. His claims could mean serious trouble for the police.

Taken off the case, Si-mok and Yeo-jin return to their work on the police-prosecutor council. Tae-ha and Bit head to a sensitive meeting together.

Kang Won-chul weighs a dilemma, and fields questions from Si-mok about the deceased attorney. A young prosecutor has something to show Si-mok.

A suspect is arrested, but Dong-jae remains nowhere to be found. In the interrogation room, Si-mok and Yeo-jin try to draw out a confession.

While getting to the truth about the night of the attorney's death, Si-mok and Yeo-jin learn about the involvement of a mystery person.

Details of the cover-up become public, but Si-mok isn't finished asking questions. The police-prosecutor council is called off.