Taemin is a murderer and the police have been after him for years with only his description. He's killed 21 people that the cops know of. He forces his brother Kibum to help, but he doesn't make Kibum kill. Kibum is terrified of him but can't refuse or tell cops because Taemin threatens to kill him

you are a cop who has been helping investigate the murders and trying to find the murderer. at a grocery store one day, you meet taemin

he glances at you, he knows you're a cop