Will is twelve years old and he's just killed a man. Now he's on the run, determined to discover the truth about the father he has never known. Then Will steps through a window into another world - the dangerous world of Cittagazze, where soul-eating Spectres haunt the streets, and a strange, savage girl called Lyra Silvertongue is searching for Dust. Their meeting is no accident, for his mission and hers are linked in an extraordinary way. Together they must reach the mysterious tower, Torre degli Angeli, to find a powerful and secret object that people from many worlds would kill to possess.