Modern youth Zhang Shaoqin travels through time to the Great Tang dynasty. Relying on innate divine strength, he becomes a disciple of Sun Simiao and saves the amnesiac princess Li Xiang. The two live together and marry in a rural village. Zhang Shaoqin establishes himself in Chang'an through medical skills, brewing, and modern knowledge, and gets embroiled in the imperial succession struggle. During the Xuanwumen Incident, he assists Li Shimin in executing enemies and uncovers Li Xiang's identity, becoming an imperial son-in-law and promoting Great Tang's reforms through troop training, education, and technology.