The female protagonist is the legitimate daughter of the Yongning Hou Mansion. She takes the initiative to enter the palace as a "companion reader" (accompanying the princess to study) in order to help her sister who has entered the palace to become a concubine. In fact, she helps her sister deal with interpersonal relationships in the harem and avoid being framed by other concubines; the male protagonist is the princess's personal eunuch who is a personal companion of the concubine. His true identity is the concubine of the Zhongyong Hou Mansion (he was framed due to internal fighting in the family and was forced to purify himself and enter the palace to avoid trouble, but in fact it was a fake purification). When the two first met, the heroine was using a "chain plan" to help her sister resolve the "poisoning" suspicion. The hero secretly reminded her that she had "ignored the people in the imperial kitchen." The heroine realized that he was not an ordinary eunuch, so she used the "cake code" to communicate with him: she helped the hero deliver family news outside the palace, and the hero helped her analyze the situation in the harem. In the process, the heroine relied on the "back house strategy" to help the hero find out the mastermind behind the family's internal strife. When the heroine was suspected by the queen, the hero used a "bitter flesh trick" to help her escape. In the cooperation with "each purpose", the two gradually discovered that the other party was the one who understood them, but they were trapped by the shackles of their "eunuch identity".
