16 Episodes · Premiered June 10, 2017 · Ended July 30, 2017
Though he is rational, a childhood brain surgery leaves prosecutor Hwang Shi Mok to lack emotion. Cold and lonely, he's one of the only prosecutors not involved in corruption. When he meets Police Lieutenant Han Yeo Jin at a murder crime scene, they join forces to eradicate corruption at the prosecutor's office and solve a serial murder case.
As a teen, prosecutor Hwang Shi 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 Shi Mok to review the CCTV clip. At the Yongsan police station, he runs into officer Han Yeo Jin.
Shi Mok volunteers to appear on live national TV to discuss Kang Jin Sup. He also makes a bold promise to find the culprit within two months.
Rumours quickly spread about Shi Mok's violent nature. Regardless, he persists in his investigation. He finds his mentee, Young Eun Su, suspicious.
Shi 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 Shi Mok's innocence.
Shi 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 Shi Mok, who warns her of the consequences.
Shi 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.
Shi 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, Shi Mok discovers that an intruder has left something in his bedroom. Yeo Jin and Gun come over right away.
Yeo Jin suspects a new killer is involved in the latest murder incident. Meanwhile, Shi Mok collapses after leaving the autopsy.
Yeo Jin collects evidence as Shi Mok interrogates the suspect. Many questions get answered, but the most important problem of all remains to be solved.
Shi 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.
