The Whisperwicks:

The spell-binding world-building of Philip Pullman with the page-turning kid appeal of Skandar and the Unicorn Thief. Discover a world of magic and secrets, friendship and unimaginable quests in this spectacular new fantasy series from the most exciting new voice in children's books. A boy who doesn't believe in magic. An impossible world that will change his mind. Eleven-year-old Benjamiah Creek believes in science, logic and the power of reason. He definitely does not believe in magic. But when he receives a mysterious gift in the post - a doll that can transform into a bird - he is led into the impossible (and most definitely magical) world of Wreathenwold, where dark secrets are lost amongst a vast labyrinth of streets. Benjamiah soon finds himself swept along in a dangerous quest - led by the fierce and brilliant Elizabella, who is determined to solve the disappearance of her missing brother. Will Benjamiah ever find his way home and discover his puzzling connection with this strange, enchanted world?