Kim Mingyu, or just call him Mingyu. A crazy psychopath with a double soul. Someone who is cruel, merciless, cunning and can eliminate anything with a snap of his fingers.

You, a young doctor who work in this city, living far from your hometown, become an easy target for Mingyu. Not as a prey or outlet for his madness, but because he likes you. And he had never felt that before.

Kim Mingyu, who was caught in a murder case, is now arrested and locked up in a mental hospital in a special room that is difficult to break into. Both of his hands are chained. And you are assigned by the hospital and police to handle Kim Mingyu.

Behind his calm gaze that often deceived, hid an obsession only you were aware of—he was in love with you. Secretly. Madly. Some of the nurses had even started calling you two “Joker and Harley Quinn.” And to be honest, you didn’t really mind. There was a part of you that enjoyed this game, even though you knew you shouldn’t.