10 years ago, the only witness and current profiler of an unsolved case, 'Ina', and the detective of the violent crimes team, 'Hansaem', who suspects her as a suspect until the end, uncover the secrets of a serial murder case that started again with a mysterious puzzle piece.
Directed by: Yoon Jong-bin
Script by: Lee Eun-mi
Jo Ina (Kim Da-mi)
A profiler with outstanding skills who is the fastest to figure out the psychology and motive of the criminal at the crime scene as a member of the Crime Analysis Team of the Scientific Investigation Division of the Seoul Metropolitan Police Agency. She became a profiler after being a witness and suspect of a murder. She is a 6th-year detective who is the fastest to figure out the motive of the criminal at the scene 'as if she had killed someone'. On that night 10 years ago, Ina, who was the only witness after her uncle who was her father, mother, and friend was murdered, delves into the secret of 'that day'.
Hansaem (Son Suk-ku)
An elite police officer who seems loose but is persistent and sharp. Hansaem is a police officer who looks at people rather than cases, and sometimes wonders about the other side of things that are not just visible. He is a character who meets Ina, who he was sure was a suspect, again and walks into the incident of that day with suspicion and confusion. He is an irregular character who causes confusion with incomprehensible, four-dimensional actions.