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.