Baek Beom – Starring Jung Jae-young

Medical examiner with 10 years of experience with the NFS
"Don’t trust everything you see. The truth is hidden behind it." He does the highest number of autopsies in Korea at over 700 case a year. He is a perfectionist who doesn’t leave any deaths unexplained, which makes him the best at what he does. He always shows up at the scene of important crimes and is all over them. He is a genius who is knowledgeable in forensics and forensic science, but doesn’t care about the living. He is socially awkward, inconsiderate and makes spiteful remarks; all three elements of social phobia.

Eun-sol – Starring Jung Yoo-mi

Rookie prosecutor with Criminal Division 8 at the Supreme Prosecutors’ Office(SPO)
"All suspects always lie. However, I can tell when they’re lying". Eun-sol has photographic memory, which allows her to remember everything she sees or hears. She is always alert and aware of her surroundings. This rookie prosecutor with a special gift is placed in the front lines of the crime at Criminal Division 8 at the SPO, a division known for the tough criminals they deal with.

Cha Soo-ho – Starring Lee Yi-gyeong

A young and passionate violent crime detective at Gangdong Police Station
A hot-tempered detective with a chiseled muscular body and good looks. He does his best to solve crimes with the pride and responsibility that he is “protecting” the people. Stella of the Toxic and Chemical Substances Division at NFS gets caught on his radar. However, it isn’t easy to get in touch with her, let alone a dinner date.

Kang Hyun - Starring Park Eun-seok

Chief prosecutor of Criminal Division 8 at the Supreme Prosecutors’ Office(SPO)
He is a smart prosecutor who wins case after case at the SPO and a gentleman known for his good manners. However, he becomes cold and domineering when dealing with criminals and doesn't beat around the bush. He was always interested in Eun-sol when he was a naïve university student. Now, she shows up in his life as a rookie prosecutor at the SPO.

Stella Hwang- Starring Stephanie Lee

Researcher at the Toxic and Chemical Substances Division, NFS
She is a 3rd generation Korean-American who studied pharmacy at one of the top schools in America. She was more interested in medicine that killed people than medicine that was used as a cure, leading her to find a job with the NFS, and becoming the best in Korea when it comes to toxic and chemical substances. All medicine becomes lethal when the quantity exceeds a certain amount. The same goes for love. A man that has 'lethal' written all over him appears in her life.