Andy and Terry live in the world's most extraordinary treehouse, featuring a giant catapult, a secret underground laboratory, a tank of man-eating sharks, and a marshmallow machine that follows you around and shoots marshmallows into your mouth whenever you're hungry. Their days are filled with wild adventures, from battling sea monkeys to avoiding burp-gas-filled bubbles. This humorous and action-packed story is told through a combination of text and fantastic cartoon-style illustrations.