The lost lands

"Sirin, Allie, and Joss have joined forces with the Silver dragon Lysander, the only creature capable of opening portals between the dragon world and the human world. But the powerful Lennix clan is following the children's every move and will stop at nothing to capture Lysander. After generations of plotting, the Lennixes--and their bloodthirsty dragon allies, the Raptors--are terrifyingly close to establishing a brutal dragon regime on Earth, just like they did centuries ago. Now it's up to the new friends to protect Lysander while searching for the lost source of dragon magic, the only force powerful enough to stop the Raptors. But first they must decide what's more important: finding the missing treasure or guarding the most important secret in the world"--Back cover.