Thursday morning on The Today Show, Al Roker announced that 39 Clues #5: The Black Circle by Patrick Carman (Scholastic) is the latest pick in his Al’s Book Club. The Black Circle pubbed on August 11.

The 39 Clues series, which will consist of 10 books in total, has more than four million copies in English in print. And the 39 Clues online game has drawn more than 580,000 registered users since it launched last September, when the series started.