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.
Crown Prince Lee Yool / Won-deuk
Hong-sim / Yoon Yi-seo
Kim Cha-eon
King
Queen Park
Prince Seo-won
Jung Je-yoon
Hong-sim's Stepfather
Kim So-hye
Kim Soo-Ji
Moo-yeon
Eunuch Yang
Lord Park Sun-do
Goo-dol
Kkeut-Nyeo
Park Bok-eun
Young Lee Yool
Young Hong-sim / Yoon Yi-seo
Young Yoon Seok-ha
Dong-joo