Jang-soo is a judo instructor who is indifferent to everyone but his daughter. One day he realizes he can see Tae-jin, a ghost who used to be a devoted police officer. Tae-jin asks Jang-soo to help solve the case that took his life away from him.
Soo-kyung works as a reporter. She has an older brother, Sung-ho, and younger sister, Joo-mi. She thinks of her two siblings as burdens. One day, Nak appears in front of them. He is their youngest sibling.
