At the end of the Nan Dynasty, the two parties of the Crown Prince and the Eldest Prince fought for power. Under the guidance of Lord Xiao Lin Zhou, the Crown Prince's group was getting powerful gradually. But Xiao Lin Zhou's great merits made the Crown Prince feel insecure. So the Crown Prince sent Qin Che, the Ninth Prince, to live in Xiao Lin Zhou's mansion so as to prevent him from meddling in state affairs. To make both sides satisfied, Qin Che stole the official letter and hid it in The Plenilune Tower. (Source: PeeWee69 at MyDramaList)