In Harry Potter's (Daniel Radcliffe's) sixth year at Hogwarts School of Witchcraft, he finds a book marked mysteriously, "This book is the property of the Half Blood Prince", which helps him excel at Potions class and teaches him a few dark and dangerous ones along the way. Meanwhile, Harry is taking private lessons with Dumbledore (Sir Michael Gambon) in order to find out about Voldemort's (Ralph Fiennes') past so they can find out what might be his only weakness.—heather