Dragon Rider book by Cornelia Funke

A dragon. A boy. A journey. Firedrake, a brave young dragon, his loyal brownie friend Sorrel and a lonely boy called Ben are united as if by destiny. Together, they embark on a magical journey to find the legendary place where silver dragons can live in peace for ever. With only a curious map and the whispered memories of an old dragon to guide them, they fly across moonlit lands and seas to reach the highest mountains in the world. Along the way, they discover extraordinary new friends in unlikely places and a courage they never knew they had. Just as well, for the greatest enemy of all is never far behind them - a heartless monster from the past who's been waiting a very long time to destroy the last dragons on earth.