Book excerpt: Andy and Terry's 13-storey treehouse is the most amazing treehouse in the world! It's got a bowling alley, a see-through swimming pool, a tank full of man-eating sharks, a giant catapult, a secret underground laboratory and a marshmallow machine that follows you around and shoots marshmallows into your mouth whenever you're hungry. And, now, The 13-Storey Treehouse is in colour! Well, what are you waiting for? Come on up!