Sophie Briggs and the Hidden Defender

It's the final year for most of the Defenders at the School of Roots and Vines. It's hard to imagine that Sophie is beginning her senior year and planning her wedding to Marcus the following summer. The group still needs to find their 6th Defender in order to save Thicket Hall and prevent the Serpent from being unleashed. Who is it? No one seems to know, or at least they aren't inclined to reveal themselves to the other Defenders. They may not even know what they are and that could prove a challenge when they need to defend Thicket Hall. It will be up to the intrepid group of friends to find out who is the last ally and bring them into their circle. But just as they're cruising toward the end of their time inside the ancient tree, the danger grows. Five of the Six seals guarding the Serpent have been opened. The Defenders will have to fight with everything they have to prevent Caleb and the Templetons from taking control. Is this the end for Thicket Hall and the tree? Or will the Defenders find a way to save it and the school?