I will marry you someday.
100 Days My Prince
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.
Episodes
Yul falls in love with Yun Yi-seo the son of Yun Bu-jun at first sight. Yul sneaks into Yi-seo's house, but the abrupt rebellion turns her house into chaos. Yi-seo and Yul are forever apart.
Under the crown prince's command, a spinster Hong Shim is about to become a concubine of lord Park.
After losing memory, Yul becomes Won-deuk and marries Hong Shim. Awkward and unfamiliar marriage begins.
Hong Shim is busy taking care of the mess that useless Won-deuk caused. In the palace, people are sent to Mt. Cheongwoosan to find the missing crown prince.
Cha-eon searching for the crown prince finds the corpse in the prince's outfit at Mt. Cheongwoosan.
At the market, Hong Shim chases after a guy who looks like her brother. While Kim Cha-eon hurriedly prepares a funeral for the crown prince, Je-yun is busy solving the puzzle that the prince left.
With the secret letter that Yul left, Je-yun asks Kim Cha-eon to meet privately. Won-deuk who was looking for Hong Shim gets attacked by the gangsters.
Kim Cha-eon pressures the king to depose the queen and the prince Seo-won. Hong-shim is uncomfortable about the present that Won-deuk gave her.
Yul figured that he is not Won-deuk after all. To find the truth, he goes to Hanyang with Gu-dol. Je-yun becomes the new lord of Songju province and meets Hong Shim.
Won-deuk and Hong Shim realize feelings for each other. As the day when Hong Shim and her brother promised to leave comes, Hong Shim's concern deepens. The king who feared the increasing power of Kim Cha-eon meets Jeong Sa-yeop.
Won-deuk and Hong Shim prepare for a fleeting together. Je-yun starts investigating Won-deuk's real identity. While Cha-eon is missing after being attacked by the assassins, people suggest Seo-won as the crown prince.
Won-deuk comes back as the crown prince Yi Yul, but the palace doesn't feel like home, and can't stop worrying Hong Shim.
Hong Shim tries to avoid Yul to leave with Mu-yeon. Due to the scheme of the queen, Yul attends the banquet to welcome the ambassador from Ming.
In Hanyang, Hong Shim looks for Mu-yeon. In the meantime, Yul solves the puzzles with Je-yun to find memory.
Yul recalls everything from the past and goes to So-hye. Hong Shim and the Songju province neighbors go to Kim Cha-eon's house to find Mu-yeon.
For Yi-seo, Yul goes to war. There, he encounters Kim Cha-eon's private soldiers.
