Chen Mo, a young man from the modern era, travels back in time to the Great Qin dynasty and becomes a laborer at the Jiuyuan mines for five years. Just as the First Emperor falls seriously ill, he risks his life by presenting medicine and tearing down the imperial edict seeking a physician. After enduring trials in which condemned prisoners test the medicine, he finally earns the emperor's trust. Chen Mo then relies on the Imperial Workshop Directorate to create soap, the curved-shaft plow, paper, and gunpowder, improve agricultural tools and military equipment, and promote competitive bidding for construction projects. He also seeks out talented figures for Qin, including Xiao He, Han Xin, and Liu Ji. Recognized by Ying Zheng, Chen Mo is ennobled and appointed Fusu's tutor. However, his reforms threaten entrenched interests, and he faces a deadly assassination attempt. The season ends with the Heaven-worshipping ceremony in Yongcheng: Chen Mo is granted the title Marquis Wending and presents a globe, while Han Xin heads to Jiuyuan to train troops. The secret of Chen Mo's time-traveling identity remains known only to the audience.