The Gu family guarded the northern frontier in full force. Before Gu Chenzhou set out on campaign, his fiancée, Princess Zhaoning, in order to help the top scholar Xie Huaijin win merit, swapped the true military report and withheld the imperial decree for troop withdrawal, causing the Gu family to be surrounded by one hundred thousand iron cavalry and all of them to die in battle. After his death, Gu Chenzhou is reborn, returning to the day the fake military report was delivered. Seeing through the plot, he plays along, joins hands with Shen Qingwu of Yunzhou to crush the Northern Di, and saves his entire family. Upon returning to the capital, he petitions to rescind the engagement, and Zhaoning is placed under house arrest. In the end, Gu Chenzhou marries Shen Qingwu, they jointly guard the northern frontier, investigate and expose Luo Kai's treason, and protect the mountains and rivers in peace, with all old friends safe and sound.