Adult fans of J.K. Rowling can rejoice: She has a new novel coming, for grownups. The kids will have to wait and see. The author of the mega-selling "Harry Potter" series has an agreement with Little, Brown in the United States and Britain to release her first adult novel, the publishers announced Thursday. The title, release date and details about the book, long rumored, were not announced. A neighbor of Rowling's in Edinburgh, author Ian Rankin, tweeted Thursday that he thinks Rowling has written a mystery novel.