In the prosperous and alienated "Cloud City", two young people who have nothing to do with each other - Lin Xiaoman, an Internet operator who is chased by KPIs every day, and Shen Xinghe, the store owner who guards old bookstores and mysterious ancient books. Because of an old book that suddenly glows, they start a fantasy life of "memory exchange". During the day, Lin Xiaoman pretended to be Shen Xinghe and stared at ancient books, and had to deal with the "weird people" who came to the bookstore to find trouble; at night, Shen Xinghe was working on a plan on the computer in Lin Xiaoman's rental house, and was forced to collapse by the client's "colorful black". From the initial dislike of each other, the two started to work together to solve the troubles in life. In the process of "living for each other" again and again, they discovered each other's softness hidden under the strong appearance, and also revealed the secrets of "understanding" and "redemption" behind ancient books. In the end, they not only found a way to stop the exchange, but also found the courage to face life side by side, proving that even if they live in a mess, they can still find their own little happiness in the chaos.
