J.K. Rowling has dropped a big clue about the seventh and final Harry Potter book. Appearing at the Edinburgh International Book Festival on Sunday, Rowling told a group of fans that the young wizard "will survive to book seven." Asked to reveal the title of the last installment, she replied: "I'm not going to tell you. I'm sorry. My agent would have me hunted down and killed." Yeah, but at least we'd know the title.