My rating of 3 stars is probably lower than what my 4th and 5th grade readers of animal-fantasy will give it. For them, the ability for animals, zoo and those thought to be extinct, to travel between the natural world and a more fantastic one is likely to grab their attention immediately. Throwing in a group of four friends with a treehouse fort who seek out adventure, a missing club member, developing relationships between humans and animals, evil Sasquatch creatures, and some magic means that I will buy this series for both my libraries. It is my hope that in future installments that Chick backs off the over-describing and the grandstanding/gushing done by Mr. Darby as he pleads his case for the saving of the Secret Zoo and the council that supports its existence. I am also hoping for a bit more depth in the character development of our four Action Scouts and more subtlety in setting us up for subsequent books. With this being his first book and it having such a unique premise, I am looking forward to watching the series unfold and improve in literary quality. But I will purchase them one at a time as I read them to be sure that aspect does improve. I recommend this book for readers in grades 4-8 who enjoy series such as Mull’s Fablehaven and O’Hearn’s Pegasus.