In the 6th episode of "Memorist," a flashback of Han Su Mi (Lee Se Young) appeared of when she was at a young age and witnessed the death of her father. She hid in her sleeping cabinet to keep herself safe and live in the memory of her mother. When she returned from school, she stayed inside the cabinet and fell asleep. The time she woke up, she heard a strange sound. She looked at the keyhole and saw a shadow of a man holding a knife, while her father was tied around the chair, covered in blood.
Growing up, Han Su Mi focused on research to find the murderer of her father but to no avail. They just wouldn't believe her. The killer is still on the loose and even if she holds a high position, she will never stop.
At the crime scene, Dong Baek (Yoo Seung Ho) came in early and felt a relief to see Han Su Mi not in danger. He realized that the little girl in his vision was Han Su Mi. They both discovered that the killer knows both of them. Han Su Mi thinks that the killer is the same person who murdered his father 20 years ago. With all their efforts, Dong Baek and Han Su Mi weren't able to catch the person who tortured the artist and cemented the bodies.
Desperate to find the answers, Han Su Mi invited Dong Baek to her house. She offered if they can work together with the recent case. Dong Baek accepted her offer. As they reached her house, Dong Baek saw all the articles and updates Han Su Mi collected for the past years.
Further to their data gathered, they asked Kyung Tan to check the police who handled the case of Han Su Mi's father. It was 20 years ago, and back then the case was transferred from one detective to another. The last officer who closed the case was Lee Shin Woong. He is the current Deputy Chief of the command center.
At the onset of their discussion, Dong Baek realized that among all the dead bodies and evidence they missed one witness. Dong Baek told Han Su Mi to allow him to scan her memory again. By any chance, they missed something from the past. Hesitant with Dong Baek's recommendation she's afraid to recall the past. She insisted that all her statements are already in the reports. Dong Baek persuaded her to allow him to read her memories. He continued that Han Su Mi always used her logic and detailed profiling. He wanted to use his telepathic abilities with her. Han Su Mi, in thorough consideration, agreed with Dong Baek.
Dong Baek touched Han Su Mi's shoulders and saw the time when her father was murdered. He approached the killer and saw a fake prosthetic mask. He also discovered that the reporter who Han Su Mi suspected was not alone. The night his father died, the reporter arrived with his cameraman earlier than the police respondents.
Han Su Mi reached out with her team and requested for profiling the cameraman. They discovered that the cameraman knows about prosthetic making. He stopped working and went overseas. As they checked, the former cameraman has returned to South Korea. They got the address and headed to the man's house. Before they could open the gate, a man on the street was walking toward the house and they met face to face.
