Because Li Shimin launched the Xuanwumen rebellion, he killed the Prince and Li Yuanji, the king of Qi, and coerced him to abdicate. Tang Gaozu was saddened by the tragic deaths of his two sons, but he couldn't kill Li Shimin. Angry at Kou Zhong and Xu Ziling, he asked Li Shimin to commit suicide before he ascended the throne. Li Shimin was forced to do so. As early as when Cui disappeared, he knew that he had finally died at his hands.

As mentioned in episode 42, episode 42:

Yuan felt very sad about the death of Cheng and Yuan. He wanted to punish the people, but in the end he was unwilling to hand over the throne, thus avoiding a war. Yuan's only condition is to ask the people to explain the Xuanwumen incident and get rid of Ssangyong.

People always want to get the throne, but they don't want to hurt their comrades who have helped them. They are deeply contradictory. They invited Ssangyong to have tea at Xuanwu Gate, and they agreed to keep the appointment, no longer fearing death, but bravely facing the prophecy of Heshibi. Ssangyong said goodbye to his beloved before going to the meeting, and everyone was reluctant to go. In order to explain to Yuan, the people finally killed Shuanglong in the land of Xuanwu Gate, and in the same year they ascended the throne, leading the Tang Dynasty into a peaceful and prosperous era.

Extended data:

Brief introduction to the story of "The Legend of Datang Shuanglong";

Shi Zhixuan, the evil king, is skilled in martial arts, but he is afraid that his evil martial arts will become a disaster in the future, so he freezes himself in the evil king's tomb with the evil emperor relic who sealed his martial arts. The only key to enter the Evil King's tomb is the secret of martial arts-longevity tactic, so everyone in the Jianghu wants it, but it has been lost in the Jianghu for many years and no one knows its whereabouts.

On the other hand, Kou Zhong (Ram Ramon? ) and Xu Ziling (Ng Cheuk Hai? Although they have been stealing for a living, they are gifted and want to learn a good martial arts, so they want to learn from the local Shilong Taoist priest in the future. Unexpectedly, when I went to find Shilong, I found Shilong fighting with a woman with high martial arts, Jun Fu Chuo. It turns out that Shilong stole Jun Fu Chuo's longevity tactic, and everyone in the Jianghu wanted it.

After a fierce battle, Fu Junchuo got back the "longevity tactics", but she was also seriously injured. Kou Zhong and Xu Ziling escaped with her. At this time, Yu Wenhuaji of the Imperial Guard led a group of people to grasp the tactics of immortality. Fu Junchuo knew that if the three of them walked together again, they would definitely not run away, so she gave the longevity tactic to Kou Zhong for safekeeping, and then left alone with the pursuer. Kou Zhong and Xu Ziling, who claimed to be Yangzhou Shuanglong, began their Jianghu trip.

Baidu encyclopedia-biography of Datang Shuanglong