Synopsis: In the underworld of a fictional city, Jang Tae-yeong (Kim Soo-hyun) is a successful gang boss and owner of a large casino. Disturbed by an entirely different personality that lies within himself, Jang decides to seek the help of Dr. Choi Jin-ki (Lee Sung-min). To help Jang be rid of the other personality, Dr. Choi comes up with an elaborate plan which Jang follows through with, but it yields unexpected consequences. What then ensues is a battle between the real and fake Jang Tae-Yeong.