Time travel to Fang Xuanling, the most useless concubine, Fang Yiyu, a doctor of science and engineering, holds the technology tree of the early Tang Dynasty, and is assassinated by the five surnames. When the heyday of Zhenguan was brought forward a hundred years to ignite the industrial fire, he had to make a choice on the night of Li Chengqian's rebellion. What is not recorded in the history books is the century-old entanglement between him and the three women between gears and poems...
