The heartless horde supervisor Jang Dong-soo experiences a brutal assault which he scarcely makes it out alive, yet his notoriety for being a South Korean mafia beast is shattered. The best way to tidy up his notoriety is to discover your assailant and deliver retribution savagely. To do his vengeance, Jang Dong-soo chooses to collaborate with Detective Jung Tae-seok, who has gained notoriety for murderous in the body, to discover his attacker. They before long understand that the man they look for is for sure a sequential killer known as K.