100 Days My Prince

Yul falls in love with Yun I-seo, the daughter of Yun Bu-jun, at first sight. Yul sneaks into I-seo's house, but the abrupt rebellion turns I-seo's house into chaos, and the two are torn apart.

Crown Prince Yul is poisoned on a day when the drought is severe. While the king searches for the culprit, Yul heads to Mount Cheonu for the rainmaking ritual. The crown prince orders all spinsters and bachelors to get married. Hong-sim, a spinster living in Songju, is about to become Lord Park's fifth mistress.

After losing his memory, Yul becomes Won-deuk and marries Hong Sim. The two begin their awkward and unusual marriage journey.

Hong Shim busily cleans up the mess that useless Won-deuk caused. Meanwhile, the palace sends people to find the missing crown prince.

Hong-sim takes care of Won-deuk after he faints, and Won-deuk slowly opens up his heart to her. Hong-sim goes to Hanyang and meets Je-yun at Mojeong Bridge. Meanwhile, Kim Cha-eon and the palace soldiers find a corpse in the prince's outfit at Mount Cheonu.

Hong-sim chases after a man who looks like her brother at the market. While Kim Cha-eon hurriedly prepares a funeral for the Crown Prince, Je-yun tries to solve the puzzle that the prince left behind for him.