In an accident, the soul of a modern young man traveled to the Tang Dynasty and became the son of a good-for-nothing Duke. Because of Li Shimin's pity, he was able to enter the palace as a bodyguard, but due to a strange combination of circumstances, Li Shimin was sterilized. This accident completely changed the fate of Datang.
Relying on modern military techniques and historical knowledge, the protagonist moves step by step in the court and makes secret plans. He took advantage of his position to have relationships with the concubines and even the queen, causing them to give birth to many princes and grandchildren without their knowledge. These princes and grandsons will become his key chess pieces in controlling the future of Datang.
As time goes by, the protagonist gradually gains power and becomes a force that cannot be ignored in the court. However, paper cannot cover the fire after all. In an accident, the identity of the biological father of the prince and grandson was exposed. The moment the truth was revealed, Li Shimin died in despair and Li Zhi ascended the throne.
The protagonist did not fall because of this, but became the emperor behind the scenes, assisting the development of the court, helping the Tang Dynasty to unify the world, and ensure peace and prosperity for the country and the people. Surprisingly, when the royal scandal was leaked to the public, the whole people supported his status as the Supreme Emperor. Because in their eyes, this wise man from the future is the one who can truly lead the Tang Dynasty to glory. This is a film where there is only a contest between wisdom and power, a game between the court and the harem. How will the protagonist leave his own legend in the long history of Datang? Everything is in "Across the Tang Dynasty: I am the biological father of the princes".
