A mother and a daughter in Yangjeong-dong appear dead, while the son survives; the investigators feel that this is a murder, so they start digging in; they find a suspect, a female neighbor living in the same building, and start searching her house.

We continue to go through the investigation of the murder case in Yangjeong-dong; the prime suspect keeps denying the charge and the investigators have difficulty finding definitive evidence as she used to be the victims' close acquaintance.

The detectives of Pyeongtaek Police Station begin investigating a robbery case; a man is blackmailed into giving the group his debit card and his bank account passcode; the case leads to a woman and two men owning and using drugs.

The detectives investigate a blackmailer in Gyeonggi-do; he blackmails illegal massage parlors and extorts money out of them; he turns his phone off and hides around the country, but the detectives get all the information they need to find him.

The Drug Investigation Team of Busan Jin Police Station guides us through the arrest of drug addicts; they share that drug offenders are quite different from regular criminals.