The story is about a man, with a double identity. Ha Dae-Cheol played by Joo Sang Wook is a righteous prosecutor, but at night he wears a mask and seeks to punish those that the law could not. Yoo Min-Hee played by Kim Sun Ah is a female detective in charge of the violent crime division.

During the day, Ha Dae-Cheol is a righteous prosecutor, but at night he wears a mask and seeks to punish those that the law could not. Yoo Min-Hee is a female detective in charge of the violent crime division.