In the nineteenth year of Zhenguan, Li Changan was dragged into the court by his master Li Chunfeng's will.
Military rations, calendars, palaces - three seemingly unrelated "accounts", behind them are the national chess game of the entire Tang Dynasty.
He thought he was just a temporary worker who knew how to count, but he didn't know that he had already become the last move laid by his master.
For decades, he worked among emperors, generals and ministers, using each account to influence the direction of history.
When all the truth came to light, he discovered that the most difficult thing in the world to settle is not the debt, but the human heart.
