Song Ha-yeong pursues a criminal known for targeting young women. Kook Yeong-su looks to form a team of criminal behavioral analysts.

Ha-yeong consults a criminal to understand a killer’s motives. An arrest leads to a startling interrogation session and a break in the case.

The grisly murder of a child catches the attention of Ha-yeong and Yeong-su. A determined police captain clashes with the team.

When a suspect’s home is searched, the police make a gruesome discovery. Ha-yeong and Yeong-su grow frustrated as the investigation continues.

A crooked new police chief causes trouble for the team. The deaths of a professor and his wife touch off a series of brutal murders.

Yoon Tae-gu and Kim Bong-sik seek to set boundaries on the behavioral analysis team. A complex investigation sends the police down a twisted path.

Ha-yeong spends time with his mother on his birthday. With two killers on the loose, the investigators are faced with high-pressure stakes.

A chase takes a risky turn. When a suspect asks for a high-ranking officer, Ha-yeong hatches a plan. A search for victims' bodies continues.

The behavioral analysis team agrees to an interview with a journalist. Ha-yeong seeks to enter the killer’s mind, but it takes a toll on him.

During interviews and crime scene reenactments, Ha-yeong and the police dive deep into a ruthless suspect's psyche and past trauma.

A horrific accident forces Ha-yeong to reflect on the mental impact of his work. Meanwhile, two people go missing from a karaoke bar, raising suspicions.