Z is for Zack - now available in English! The original Zackie Mostert series has thousands of young fans - and now there's also a reading series, perfect for beginner readers. Each book in the series features bright full colour illustrations and simple, easy-to-read text that will make these fun-filled stories accessible to young readers. 3. Tree House Trouble Zack and Vincent are building a tree house. It's going to be the best tree house in Zucchini Street! But Zack's sister and her best friend also want to play in it. Zack and Vincent make a sign: NO GIRLS! But can they keep the girls out of their tree house?