The girl Lin Wan found a glowing ancient book in the old library left by her grandmother. When she touched it, she was instantly drawn into a rift in time and space. She traveled to Shanghai during the Republic of China and became the daughter of a bookstore owner. There is a star map hidden in the library that can connect the past and the future, and the "Sunset Star" recorded in ancient books is her only chance to return to the modern world.
In the process of searching for the star map fragments, she met the mysterious clockmaker Azhe, and the two teamed up to decipher the secret of the library. As the sun sets, Lin Wan discovers that the library is not only a passage through time, but also the key to protecting family memories. In the end, she made a choice in the starlit library: return to the familiar modern times, or stay in the Republic of China to protect the secrets of the library?
