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.
Lee Yool falls off a cliff and nearly dies in an attempted assassination. He loses his memory, and wanders for 100 days under a new name and personality. During this period, he meets Hong Sim, head of the first detective agency in Joseon.
