The world of Cittagazze is an unsettling place: silent, empty streets, the threat of horrible death from the soul-eating Spectres from which only children are safe. Into this world comes Will, a 12 year old boy who has just killed a man. On the run, he meets a strange young girl called Lyra. Their paths take them to the mysterious Torre degli Angeli, where they must somehow acquire Cittagazze's most important secret: an object which people from many worlds would kill to possess. But Will has his own task as well: he must find the father he has never known. Could it be that this quest, and Lyra's, are a part of the same larger one? The Subtle Knife is part 2 of the trilogy His Dark Materials.