Shen Zhibai, a doctor of modern astrophysics, accidentally traveled to the Tang Dynasty's Tianjian in the prosperous Kaiyuan Dynasty, but became a prisoner to be executed for his speech. On the execution ground, relying on his precise interpretation of the celestial phenomenon of "Venus seeing daytime", he managed to save people, but he also fell deeply into the power whirlpool of Si Tianjian.
In this era where people believe deeply in the connection between heaven and man, he relies on astronomical knowledge that spans over a thousand years, uses the stars as his chess, and arithmetic as his blade: he accurately predicts the moment of the lunar eclipse, solves the mystery of the armillary sphere fraud, and launches thrilling contests with conservative dignitaries on the observatory. From a death row prisoner to "Doctor Zhitian", he not only has to correct the tampered star map, but also has to face the undercurrent of the court struggle.
When Ziweiyuan's alien star shines and urgent reports from the Anxi Protectorate come frequently, Shen Zhibai gradually discovers that hidden deep in Si Tianjian is a secret that can shake the foundation of the empire...
