Li Yangzheng, the Dragon-Slaying Holy Lord, returns to the capital to break off his engagement, only to have Prince Zhu Guoan, the Prince Who Guards the Nation, publicly cling to his leg and insist on making him his son-in-law. Refusing to let go, the prince is determined to take him as a live-in son-in-law. Dressed in ragged clothes that conceal his true strength, Li Yangzheng plays the part of a frail young scholar in the prince's residence. In secret, he eliminates assassins, destroys enemy strongholds, and saves a critically ill patient with a single acupuncture needle. Jiang Siyu recognizes his true identity from his physique, while the renowned physician Da Shenyi realizes that the Holy Lord is the legendary dragon slayer. When the Grand Tutor catches a glimpse of his eyes, he is secretly shaken. Everyone believes he is a destitute beggar, unaware that this live-in son-in-law is the very Holy Lord who fought for seven days and nights at Duoyun Mountain, forcing the Gate of Hell to submit to his command. The martial world does not know who I am. I only seek to keep this household safe and peaceful.