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.
Doh Kyung-soo
Crown Prince Lee Yool / Won-deuk
Nam Ji-hyun
Hong-sim / Yoon Yi-seo
Cho Seong-ha
Kim Cha-eon
Cho Han-chul
King
Oh Yeon-ah
Queen Park
Ji Min-hyuk
Prince Seo-won
Kim Seon-ho
Jung Je-yoon
Jung Hae-kyun
Hong-sim's Stepfather
Han So-hee
Kim So-hye
Heo Jung-min
Kim Soo-Ji
Kim Jae-young
Moo-yeon
Jo Hyun-sik
Eunuch Yang
Ahn Suk-hwan
Lord Park Sun-do
Kim Ki-doo
Goo-dol
Lee Min-ji
Kkeut-Nyeo
Lee Jun-hyeok
Park Bok-eun
Jung Ji-hoon
Young Lee Yool
Heo Jung-eun
Young Hong-sim / Yoon Yi-seo
Jeong Joon-won
Young Yoon Seok-ha
Do Ji-han
Dong-joo
Doh Kyung-soo
Crown Prince Lee Yool / Won-deuk
Nam Ji-hyun
Hong-sim / Yoon Yi-seo
Cho Seong-ha
Kim Cha-eon
Cho Han-chul
King
Oh Yeon-ah
Queen Park
Ji Min-hyuk
Prince Seo-won
Kim Seon-ho
Jung Je-yoon
Jung Hae-kyun
Hong-sim's Stepfather
Han So-hee
Kim So-hye
Heo Jung-min
Kim Soo-Ji
Kim Jae-young
Moo-yeon
Jo Hyun-sik
Eunuch Yang
Ahn Suk-hwan
Lord Park Sun-do
Kim Ki-doo
Goo-dol
Lee Min-ji
Kkeut-Nyeo
Lee Jun-hyeok
Park Bok-eun
Jung Ji-hoon
Young Lee Yool
Heo Jung-eun
Young Hong-sim / Yoon Yi-seo
Jeong Joon-won
Young Yoon Seok-ha
Do Ji-han
Dong-joo
Doh Kyung-soo
Crown Prince Lee Yool / Won-deuk
Nam Ji-hyun
Hong-sim / Yoon Yi-seo
Cho Seong-ha
Kim Cha-eon
Cho Han-chul
King
Oh Yeon-ah
Queen Park
Ji Min-hyuk
Prince Seo-won
Kim Seon-ho
Jung Je-yoon
Jung Hae-kyun
Hong-sim's Stepfather
Han So-hee
Kim So-hye
Heo Jung-min
Kim Soo-Ji
Kim Jae-young
Moo-yeon
Jo Hyun-sik
Eunuch Yang
Ahn Suk-hwan
Lord Park Sun-do
Kim Ki-doo
Goo-dol
Lee Min-ji
Kkeut-Nyeo
Lee Jun-hyeok
Park Bok-eun
Jung Ji-hoon
Young Lee Yool
Heo Jung-eun
Young Hong-sim / Yoon Yi-seo
Jeong Joon-won
Young Yoon Seok-ha
Do Ji-han
Dong-joo