One summer night in Shanghai, Zong Ying bumps into an unexpected visitor at home who claims to also be the owner of an old apartment No. 699 in Shanghai. Every night, he time travels from 1937 to modern times and goes back by the morning. He even has proof of his identity as an attorney of the Republic of China. Although Sheng Qing Rang tried to convince her that he was from another time period, the level-headed Zong Ying was quick to brush it off as nonsense. Yet when he disappears before her eyes, she has no choice but to begin accepting the fact. What began as an accidental encounter has found purpose. As Zong Ying and Sheng Qing Rang go back and forth between two eras, the two people who were quite restrained when it comes to love gradually go from friends to confidantes and finally, lovers. However, death has seemingly cast a shadow on Sheng Qing Rang's future as the Battle of Shanghai broke out. It is an extravagant hope for the couple to simply be able to stay together. In the flames of war, two people who do not belong to the same time and space have become the most important footnotes in each other’s lives. Adapted from the popular time-travel themed novel with the same name "Ye Lu Ren" (夜旅人) by Zhao Xi Zhi (赵熙之).