Lin Shen never thought that the books donated to the library by Cheng Yuan contained a secret that lasted for several years.
A "Children's Psychology" with "Lin Shen Cun Nian" written on the title page, a scrawled warning sandwiched between the pages - "The seventh one. Be careful.", And the vaguely legible "Not true" blurred by water stains.
Seven books, seven visitors, one undeliverable reminder. When Lin Shen followed the guidance of the old book pages and tried to piece together the truth, he found that every step he took was like stepping on a chessboard that Cheng Yuan had already laid out. What did the person who gave the book want him to find? And who is that "seventh visitor"?
