David Walliams, hailed as "the heir to Roald Dahl" by The Spectator, burst onto the American scene with the New York Times bestseller Demon Dentist. Now the UK's #1 bestselling children's author is back with this high-flying adventure about a boy and his grandfather, perfect for fans of Jeff Kinney and Rachel Renee Russell.

Grandpa is Jack's favorite person in the world. It doesn't matter that he wears his slippers to the supermarket, serves