Reckless III: The Golden Yarn - Cornelia Funke

Jacob Reckless continues to travel the portal in his father's abandoned study. His name has continued to be famous on the other side of the mirror, as a finder of enchanted items and buried secrets. His family and friends, from his brother, Will to the shape-shifting vixen, Fox, are on a collision course as the two worlds become connected. Who is driving these two worlds together and why is he always a step ahead?

This new force isn’t limiting its influence to just Jacob’s efforts – it has broadened the horizon within MirrorWorld. Jacob, Will and Fox travel east and into the Russian folklore, to the land of the Baba Yaga, pursued by a new type of being that knows our world all to well.