The Balloonmakers series does not have a new book coming out soon. The latest book, The Spy with the Red Balloon (Book 2), was published in October 2018.
The first book in the Balloonmakers series, The Girl with the Red Balloon, was published in September 2017.
The Balloonmakers series primarily falls into the Fantasy genre. This young adult series was written for ages 12-17, but can be enjoyed by adults too.