After barely surviving a violent attack by an elusive serial killer, crime boss Jang Dong-su finds himself forming an unlikely partnership with local detective Jung Tae-seok to catch the sadistic killer simply known as K.

After barely surviving a violent attack by an elusive serial killer, crime boss Jang Dong-su finds himself forming an unlikely partnership with local detective Jung Tae-seok to catch the sadistic killer simply known as K.