Book three in this fast-paced and exciting series for middle grade fantasy, mystery, and animal buffs. Noah, Megan, Richie, and Ella are the Action Scouts; friends whose tree house overlooks the Clarksville City Zoo. When they discover a magical world hidden within the zoo, they are swept away on an adventure in which penguins can fly, a mysterious figure lurks in the shadows, and the scouts are enlisted to help Mr. Darby, who is in charge of the Secret Zoo. But will the scouts be able to fight against the dangerous sasquatches who have escaped the zoo and threaten their town? There's only one way to find out if the four friends training as Crossers can help save the Secret Zoo. The author originally had the idea for The Secret Zoo when he was nine and wondered what would happen if zoo exhibits had secret doors that allowed kids to go inside--and the animals to come outside. He brings that sense of adventure and excitement to this story, making it a favorite for home and classroom reading along with such middle grade fantasy favorites as The One and Only Ivan.