The Trumpeter of Krakow

A Newbery Medal Book: It is the fifteenth century in eastern Europe and the shimmering, pure Great Tarnov Crystal is coveted by all who seek the supreme answers to Life. Obsessed be the desire to own this mysterious gem, a Tartar chieftain tracks down its hiding place - the estate of the Charnetski family of the Ukraine. Bound by an ancestral oath to this legendary crystal, young Joseph Charnetski and his family seek refuge in the city of Krakow. There Joseph is caught up in the plots and intrigues of alchemists and superstitious peasantry, of a kindly priest and a messenger of evil. What can Joseph do to save the city - and the Great Tarnov Crystal - from the plundering Tartars?