Sakura Kinomoto, a student of Tomeda Elementary returns home from school one day and finds a book in her fathers's library. Being her little curious self, she opened the book. Inside, the book had a stack of cands, "clow cards". Sakura read the first card's name aloud which accidentally triggered it's attack.
A gust of wind scatters the cards from the book around Tokyo. She opens her eyes again, a little creature named Kerberos emerged from the book thrilled to be outside again. He immediately discovers the Clow Book to be empty and grew furious! Since Sakura was the one who had the power to unlock the book and scatter the cards, it was her mission to collect the cards again before the earth corrupts...