In the autumn of the 14th year of the Republic of China, in an antique shop called "Guan Fuzhai" in Liulichang, the capital, 24-year-old Yi Jiasheng received an unsigned letter. On the back of the envelope, there was only one hexagram drawn - Ze Shui Keng. The sender of the letter is his uncle Jin Abacus, who has been missing for three years, the last minor official in the Qin Dynasty Prison of the former Qing Dynasty, and a master of Yi Xue.
There is only one sentence in the letter: "Your Majesty, don't lose your place and don't believe what you say. Come quickly."
Yi Jiasheng rushed to Tianjin, and the golden abacus was gone. In the empty room, the entire wall is covered with hexagrams - the "yin and yang" sequence of the twelve news hexagrams, each stroke and ink, recording the secret expansion of a certain force. He found a manuscript under the bed board, with a scrawled line written on the last page: "On the day of Gengzi, my wife's wealth moved in the Dui Palace. She was trapped in a golden chariot and fell into a deep valley. She was not able to face each other at the age of three. I have deduced it more than ten times, and the ending is always - the dragon has regrets."
