The twelve-year-old Xianmin Lang Qian was entrusted by his master Gu Kentang to go to the Yunjia Fortress to deliver a letter, inviting the Yun family to assist the Fourth Prince in seizing the throne. Unexpectedly, he was ambushed by the Qinling faction on the way and lost the letter, and was subsequently imprisoned by the Yun family. Yun Zhongfeng, who had a preexisting engagement with Xianmin, seized the opportunity to rescue him. Just then, the Fourth Prince arrived at the Yunjia Fortress.