Zhao Yan, the owner of a mountain homestay, unexpectedly receives four special guests — Ying Zheng, Emperor Qin Shi Huang, accompanied by Fusu, Meng Tian, and Zhao Gao, who have traveled here from the Great Qin two thousand years ago. These cross-time travelers may only stay for eighty-one days; beyond that, they will gradually fade and vanish. The four, with Zhao Yan as their guide, traverse mountains and rivers, following the cuisines of every region: they climb the Great Wall, visit the Terracotta Army pits, journey through the South of the Yangtze, and enter the Lingnan region. Amidst the daily bustle of the present world, they re-examine their achievements and regrets. Father and son grow from clashing in ideals to understanding one another; ruler and minister heal from suspicion and rift to reconciliation. Zhao Gao lets go of his obsession to change fate, and Ying Zheng lays down the weight of being an emperor. When their time runs out, three of them return to the Qin with skills for the people’s livelihood, while only Ying Zheng chooses to stay in the world of everyday life.