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