Episode 21 recap: Lu Shuangshuang is looking for an antidote for Mo Chengqian.

Mo Chengqian was severely injured while trying to save Lu Shuangshuang from an assassin. Just as the assassin was about to kill Lu Shuangshuang, Xiao Rufeng appeared and saved them both, causing the assassin to collapse. Xiao Rufeng was very concerned about Lu Shuangshuang and was about to go and comfort her when he noticed that her eyes were filled with Mo Chengqian. He stopped in his tracks and had to restrain his emotions. Mo Chengqian also noticed Xiao Rufeng's expression and was delighted to see that Lu Shuangshuang cared about him. However, Mo Chengqian no longer harbored any hostility towards Xiao Rufeng and was grateful that he had come to save Lu Shuangshuang.

Xiao Rufeng stated that it was his responsibility to save the Crown Prince and the Crown Princess. After Mo Chengqian finished speaking, he fainted. Xiao Rufeng examined him and realized that Mo Chengqian had fainted due to poisoning. Lu Shuangshuang was very worried about Mo Chengqian and was told by the imperial physician that they needed to find the legendary Qing You grass to save him. Lu Shuangshuang believed that this herb truly existed and set off alone to search for the antidote in the desolate mountains.

Lu Shuangshuang searched for a long time but couldn't find the herb, and she ended up getting lost in the mountains. She suddenly remembered that she had been saved by Mo Chengqian when she was lost in the mountains before, and now she could only rely on herself to save him. Finally, Lu Shuangshuang found the antidote. Mo Chengqian drank it, but he still didn't wake up. Lu Shuangshuang thought that she had brought the antidote back too late and started crying beside him, but to her surprise, Mo Chengqian woke up.

Mo Chengqian told Lu Shuangshuang that the King of the Underworld had allowed him to return. Lu Shuangshuang finally felt relieved as she hugged Mo Chengqian. Wei Shuyuan learned that the plan had failed, and the Third Prince became furious with embarrassment. However, she was not in a hurry and still wanted to kill Lu Shuangshuang. She didn't believe that Lu Shuangshuang's luck could be so good.