In the 14th year of Tang Tianbao, in the morning light of Zhuque Street in Chang'an, Su Jingnian, the director of the Taishi Bureau, discovered a copper coin engraved with "Kaiyuan Tongbao" but with strange patterns among a pile of astrological charts. This copper coin was exactly the same as the relic that his father Su Jingzhi carried when he died mysteriously in the Hexi Jiedushi shogunate three years ago. In order to trace the cause of his father's death, Su Jingnian was forced to be involved in a conspiracy that spanned the court and the border: the secret power struggle between Prime Minister Li Linfu and An Lushan, the changes in grain and grass in the Hexi military town, the secret messages circulating in the hands of Persian Hu merchants, and even the lychee tribute to Concubine Yang deep in the palace wall, all hidden clues pointing to the "Bone of Chang'an". The so-called "Chang'an bones" are not real bones, but a secret military defense file left during the reign of Emperor Taizong that could shake the country. Su Jinnian's family is the "bone keeper" who has guarded this secret file for generations. When the Anshi Rebellion raged toward Tongguan, Su Jinnian had to make a choice between guarding secret files and saving the people of Chang'an. Only then did he understand that the so-called "Chang'an bones" were never cold documents, but the family, country and beliefs in the blood of every Chang'an person.
