I'm not sure specifically as I haven't read it. It might be about the life of an imperial consort, perhaps her rise to power, her relationships in the imperial court, and the challenges she faces in that complex environment.
I don't know the exact main characters as I'm not familiar with this novel. But it's likely that the imperial consort herself is a main character. There may also be the emperor and perhaps some court ladies or eunuchs who play important roles.
Imperial Concubine Lu, whose original name was Lu Jiashi, was the concubine of Emperor Qianlong of the Qing Dynasty. She was born on August 12th, 1724. She was the daughter of Lu Shilong and was from Suzhou. During the reign of Emperor Qianlong, the Lu family was only granted the title of Imperial Consort Qing. It was only after her adopted son, Emperor Jiaqing, ascended the throne that she was granted the title of Imperial Consort Qinggong. Consort Lu had no children and died on August 21, 1774 at the age of 50. There wasn't much information about her family background and her early years, but her father, Lu Shilong, had no official position and was of low birth. Although the Imperial Consort Lu of Qinggong had never had children, she was deeply loved by Emperor Qianlong in the harem.