For Lin Mo, old books are containers of time, hiding the thoughts and warmth of the past; for Gu Yanqi, ancient books are the key to history, which can unlock forgotten years and stories. The two met in the quietest corner of the library through an old poetry collection from the Republic of China. One understood the texture and atmosphere of books, and the other knew the origin and value of books. They followed the clues of love letters hidden in old books, searched local chronicles and borrowed files together, and restored a love that spanned half a century. In the process of textual research and exploration, the resonance of knowledge turns into ripples of heartbeat, and the intellectual attraction is better than the passionate confession. This is a quiet love that begins with old books and ends with sincerity.