The main content of "Juvenile Detective Series: Magic Library" is an incredible investigation trip of two 13-year-old boys. The old library of Rising Sun Middle School is a mysterious forbidden area. The school rules say: "Students in our school are not allowed to enter the Second Library without permission." School rules also apply to school teachers. In fact, only the principal, vice principal and dean of the whole school have been to the old library.

One night, however, Li Xiaotian saw someone knocking at the door of the old library. Later, he learned that the boy named Bei Le ventured into the library to look for his parents who disappeared six years ago. So, are Bei Le's parents in the library? Are they alive or dead? What does their disappearance have to do with Rising Sun Middle School?