In which episode does Zhenguan rule appear?

The forty-second episode, according to the TV series Cat Network. Plot fragment: The happy relationship between Li Chenggan and his attendants is extraordinary, and all this is seen by spies sent by Lee Tae. Lee Tae thought the time was ripe, and it was time to give the prince a blow. An imperial envoy took Li Shimin by the hand and rushed into the East Palace, killing him in front of Li Chenggan and taking Li Chenggan to Li Shimin. Li Chenggan refused to admit his mistake, but angrily accused Li Shimin of his crimes. Li Shimin whipped Li Chenggan with the whip in his hand, but he also suffered great pain in his heart. Unconsciously, Wu Cairen has been in the palace for four years. She not only won the favor of Li Shimin, but also became good friends with Li Zhi, the son of Li Shimin. The Rule of Zhenguan, played by Zhang Jianya and starring Ma Yue, Jin Shijie, Ma Shaohua, Miao Miao, Ma Jingwu, Lu Jianmin, Shen Mengsheng and Ge Zhijun, was released in Chinese mainland in 2007.