Layers of dirt are lifted from a small picture largely ignored for centuries - and a masterpiece by Raphael is revealed. X-radiography discovers a second figure behind the first in a sixteenth-century royal portrait. High technology establishes for police or auction rooms whether priceless pottery is real or fake. Science can analyze works of art and restore them to their original perfection - or so it seems. But in restoration, something of the past is always lost. Will the judgments that restorers make today stand up to the scrutiny of future generations?