The Dragon Tree, legend of the Wye valley .

A thousand years ago, Azagard, the last dragon, fought a battle to the death with an evil sorcerer called Mortazar. Unfortunately after killing Mortazar, Azagard was cursed to live the rest of his life as a tree somewhere in a welsh valley, never to eat meat or fly again and only to drink rainwater from his roots.
In 2015 Cody and his best friend Shannon live in the mystical Wye Valley. It is their playground and they love exploring long forgotten footpaths, climbing trees and searching for hidden caves.
Cody's Grandfather tells Cody the legend of Azagard and Mortazar. Grandad also tells Cody the stories should be treated with respect because some are based on fact and he should be careful in the forest. Cody loves the tale but like most kids, thinks it's just a story.
Whilst exploring the valley they know so well the two friends see an otter going down a hole and stumble across a cave entrance uncovered by a recent rock fall. Curiosity gets the better of them so they enter the cave and unwittingly disturb something. The story continues at pace until almost by accident they set in motion a sequence of events that releases the dragon from its thousand year curse.
In so doing, Azagard is not the only creature reborn into the valley. Mortazar; the sorcerer who originally cursed the dragon is awoken. The children find themselves thrust into a desperate quest to get home, but Mortazar, his legion of grockles, and a soul collector from the Deephollows have other plans for them. To make matters worse, Mortazar has cast a powerful spell that has taken the entire valley back in time to when he ruled all who lived there. The children need to find a way home in a world they don't recognise. Friends they make along the way become very important, as does a certain dragon.