The series depicts the story of a fateful encounter between Do Do-hee (Kim Yoo-jung), a haughty but organised heiress of a conglomerate, and Jeong Gu-won (Song Kang), a demon who is cold and carefree, and who temporarily loses his powers. The couple embark on a contract marriage, agreeing to help each. Over time, their relationship begins to evolve into romance, but not any sooner than they each realise their romance may be dangerous to the