The Secret Zoo is an incredible world hidden beneath the regular Clarksville Zoo, where animals and humans peacefully coexist as equals. It is full of marvels. But even in the Secret Zoo, there are dangers . . . and forbidden places. When the scouts' friends are held in the off-limits sector--a never-ending maze of aquariums--Noah, Megan, Richie, and Ella must be at their most courageous.