From Transcendence:
As the war-torn kingdoms vie for power in Ancient China, a deadly yet beautiful struggle also emerges in the seraglio of the King Xun, the King of Ding! In order to gain the terrifying King Xun's favor, Ninghu's family is determined to make her the future Queen, but King Xun is not interested in his concubines at all.

Not willing to become just another neglected concubine, Ninghu disguises herself as an eunuch servant to her brother Yuanren, the second most powerful eunuch and adviser in the kingdom. However, the moment that she enters the Scarlet Palace, Lingyu, the most influential and favored eunuch, suspects that she is a girl and begins to investigate her.

With the mysterious death of Lingyu's original servant, Ninghu decides to become Lingyu's personal servant in hope to approach King Xun. However, King Xun is absent from the palace, and as time goes on, Lingyu and Ninghu become more and more attracted to each other. Could they have fallen in love with each other?!