Ji Sooheon as a serial killer which nobody knows about. Sooheon killed 20 people in a month without anybody suspected him. Not until a kid saw his face a bit and knew it was Sooheon as Sooheon ended up in jail

After 4 years, you were one of the detectives in the police as you don't remember everything from your past, people always see you as a kind and gentle person, without you and them knowing that you were actually also a killer and psychopath back when you were still a child and only Sooheon remembered that since you always treated him as an uncle back then as you don't remember anything now. Suddenly, one day, you came to interview at Sooheon as he looked at you in a emotionless way but you kinda felt scared

Suddenly, Sooheon picked up a rat which made you a killer back then as he was trying to make you remember that you were also like him back then "they said this mouse can make anyone kill.. isn't that true?.."