The Fatal Touch

In the early hours of a Saturday morning, a body is discovered in Piazza de' Renzi.
If it was just a simple fall that killed him, why is a senior Carabiniere officer so interested?
Commissioner Alec Blume is immediately curious and the discovery of the dead man's notebooks reveals that there is a great deal more at stake than the unfortunate death of a down-and-out... What secrets did he know that might have made him a target? What is the significance of the Galleria Orpiment? And why are the authorities so intent on blocking Blume's investigations?