The conclusion of the world’s most popular children’s book–Harry Potter–will finally be revealed on July 21, the publication day for the seventh and last installment of J.K. Rowling’s hugely successful book series one week earlier of the world premiere of The Order of the Phoenix movie.

“Harry Potter and the Deathly Hallows“, the 7th and last of the Harry Potter series, is predicted to be the fastert-selling book of all time, a record currently held by the sixth installment, “Harry Potter and the Half-Blood Prince.” This is because the month of July is going to be the breakout of the “Pottermania” fever because it’s the first time that the book and the movie will be released on the same month.

Bloomsbury Publishing, which handles the Potter books in Britain, said on Thursday that the series had sold 325 million copies worldwide.