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.

Je-yun uses the secret letter Yul left behind to meet Kim Cha-eon privately. Won-deuk is attacked by gangsters while searching for Hong-sim.

Kim Cha-eon pressures the king to depose the queen and Prince Seo-won. Hong-sim feels uncomfortable about the gift that Won-deuk gives her.

Yul learns that he is not Won-deuk after all. He travels to Hanyang with Gu-dol to find out the truth. Je-yun becomes the new chief governor of Songju Province and meets Hong-sim.

Won-deuk and Hong-sim realize their feelings for each other. Hong-sim's concerns deepen as the day of her and her brother's departure approaches. Fearing the increasing power of Kim Cha-eon, the king meets with Jeong Sa-yeop.

Won-deuk and Hong-sim prepare to leave together. Je-yun starts investigating Won-deuk's real identity. While Cha-eon is missing after being attacked by assassins, the King tries to appoint Seo-won as Crown Prince.

After Cha-eon comes to find him, Won-deuk comes back as the Crown Prince Lee Yul, but the palace doesn't feel like home. And he languishes in the palace worrying about Hong-sim.

Hong-sim pushes Yul out and prepares to leave with Mu-yeon. Due to the scheme of the Queen, Yul attends the banquet to welcome the envoy from Ming.

In Hanyang, Hong-sim looks everywhere for Mu-yeon. Meanwhile, Yul tries to solve the riddle that he himself secretly left Je-yun in order to get back his lost memories.

Yul recalls everything from the past and goes to see So-hye. Hong-sim and the Songju neighbors go into Cha-eon's house to rescue Mu-yeon.

Yul goes to the battlefield to save I-seo, knowing that he could die, and faces Cha-eon's soldiers that try to kill him.