Storyline:
Kang Bit-Na (Park Shin-Hye) is an elite judge with a beautiful appearance, but she is actually a demon. Her mission as a demon is to kill evil people who lead other people to their deaths and don't reflect on their actions and are unforgiven for their actions. She sends these people to Hell afterwards. One day, Kang Bit-Na meets Han Da-On (Kim Jae-Young). He has a friendly and gentle personality. As a detective, his mind is sharp and he has a keen sense of observation. But, internally, he carries pain in his mind that nobody knows about. After Kang Bit-Na and Han Da-On meet with each other, their lives change greatly.