But one day, she is attracted by a noise in her father's library. While searching for the origin of the sound, she finds a mysterious book: The Book of Clow, which she opens by accident. She then accidentally lets out almost all of the Clow Cards that were there, and only manages to keep one: the Wind Card. Through her ability to open the book's seal, Sakura discovers that she has special powers and that it is her responsibility to retrieve the scattered cards.