A Glancing Light — Aaron Elkins

Mild-mannered and law-abiding, Chris Norgren, curator of Renaissance and Baroque art for a Seattle museum, is an unlikely undercover investigator, but when a priceless stolen-masterpiece is discovered in a shipment of reproductions, Chris reluctantly agrees to find out how the painting got there. All too soon, what should have been a pleasant interlude in Italy turns into a bizarre odyssey into shady art world doings and deadly secrets...