Episode 18 recap: Yan Zhang Yun discovered that his childhood little sister was Fasha.

The Emperor agreed to let Yan Zhang Yun become the prince consort of Ning State, telling him to act like a real prince consort even if he was undercover. Fasha learned that Yan Zhang Yun was ordered to be the prince consort, so she wrote a farewell letter and gave her purse to Yan Zhang Yun. Yan Zhang Yun immediately guessed that she was the childhood playmate through this purse.

Fasha was assassinated on her way out of the capital. The Emperor decided to let Yan Zhang Yun marry the Ning State princess, secretly hoping that Fasha would return to him. Yan Zhang Yun firmly refused, but the Emperor said Ning State had agreed to a 50% tariff reduction, so he couldn't refuse this marriage.

Yan Zhang Yun left the palace troubled, wanting to investigate the cinnabar powder incident through the princess, but not wanting to marry her. The princess praised Yan Zhang Yun's archery skills, and the Emperor came to play with Fasha, so the four of them played shuttlecock together, with the princess and Emperor unable to participate, just watching Fasha and Yan Zhang Yun.

Later, the Emperor told Fasha that Yan Zhang Yun had agreed to marry the Ning State princess. Fasha didn't believe it and confronted Yan Zhang Yun, who had wanted to tell her he had no choice, but the eavesdropping princess made him say he agreed willingly.

That night, Fasha got drunk. Yan Zhang Yun, seeing her tipsy, tenderly played with her hair and confessed his feelings for her. The next day, Fasha left a farewell note and departed. A nearby assassin, following Leifu's instructions, monitored Fasha since she knew Yan Zhang Yun's true identity and had to be silenced.

Yan Zhang Yun found Fasha's letter in his room and saw the embroidered purse, realizing she was the little sister he had been searching for. Fasha was intercepted by Leifu, but blew the jade bone whistle, and Yan Zhang Yun arrived just in time to save her.

Fasha hugged Yan Zhang Yun and cried, saying she almost died. Yan Zhang Yun could no longer hide his feelings and kissed her. On the way back, Fasha held his hand, and Yan Zhang Yun promised not to go to Ning State anymore and to always be by her side.

Fasha agreed to maintain a secret relationship with him to let him continue investigating the cinnabar powder. Leifu's assassination attempt on Fasha failed, and he asked Yan Zhang Yun if he had forgotten the family hatred. Yan Zhang Yun had not forgotten, and he finally found the family that had saved him - Fasha was the little sister, and he was shocked to learn that the village had been massacred by the enemy after he was taken away by Leifu that night.

Yan Zhang Yun swore from then on to find the missing little sister. Leifu gave up assassinating Fasha, but was concerned that if Fasha regained her memory, she might turn against Yan Zhang Yun due to the calamity caused to her family.

The next day, Dao Ge was in a confused state and stole the princess's fragrance. His eyes were red and swollen. Afterwards, the imperial physician examined Dao Ge and he spoke at length about his recent experiences. At first, he felt energetic and refreshed, but later he became increasingly fatigued and even addicted to inhaling the imperial concubine's fragrance.

The imperial physician discovered that Dao Ge had symptoms of cinnabar and silver poisoning. The Empress especially went to the Emperor and said that using the imperial concubine's fragrance made one feel energized. Upon hearing this, the Emperor gave all of it to the Empress. At this time, the Wet Nurse came to request the imperial concubine's fragrance, saying the Empress Dowager greatly enjoyed it. Then Xiao Quan came and deliberately scolded his sister for not honoring the elders, telling her to give all the imperial concubine's fragrance to the Empress Dowager.

Xiao Quan, seeing Dao Ge's symptoms had already appeared, feared the imperial concubine's fragrance scandal would soon be exposed. He had Bai Yi quickly make advance preparations, and gave him a bottle of medicine, also admonishing him not to be soft-hearted and to not forget his identity as the Second Prince of Ning. Yan Zhang Yun told Wei Tian Jiao that the imperial concubine's fragrance contained cinnabar and silver powder, and that the princess must be involved with Xiao Quan.

To verify whether Xiao Quan and the princess were acquainted, Fuzhao devised a plan. The next day, Wei Tian Jiao disguised himself as the Fourth Prince of Ning and veiled his face when he came to the Xiao family's shop. The butler, thinking it was the Fourth Prince, reminded him not to be so overt, rambling on about the dangers of many eyes and onlookers. When Wei Tian Jiao removed his veil, the butler was stunned.

The butler was locked in the dungeon and refused to admit any connection to the Fourth Prince of Ning. Yan Zhang Yun knew the butler would not talk, as Xiao Quan held his family's lives in his hands. The only way was to have the butler in their grasp, so that Xiao Quan would not have peace of mind. Xueying asked Xiao Quan for permission to assassinate the butler in the dungeon, but Xiao Quan had an even better counterplan.

The next day, Xiao Quan went to the Emperor to file a complaint. At this time, Yan Zhang Yun came to the Emperor to report the evidence of the butler's collusion with Ning, but Xiao Quan claimed that if the butler had even a single injury, it would mean he had been coerced. The Emperor mediated between them and returned the resignation letter to Xiao Quan.

After Xiao Quan left, the Emperor knew that Xiao Quan's greatest love was power, but his performance in resigning just now was too poor. The Emperor instructed Yan Zhang Yun to keep good company with the princess, so that the case could be cracked quickly. At night, Yan Zhang Yun and Fuzhao slept on either side of a wall, chatting with each other into the late hours.