If I have a problem with Pears, it is that I can't remember from his titles whether I have read a title or not. Perhaps it is my lack of knowledge of art history. But I love his books while actually reading them, and Giotto's Hand was no exception.
This is #5 (of 7) in Iain Pears' Art History Mystery series, but it's the last I read! I saved it a while, knowing that after this one, there aren't any more! Objectively, this probably isn't the best of the series,but it's a solid entry. Bottando, the director of the Art Theft Squad, has an upstart after his job, and out to discredit him and his methods. He grabs onto a dead-case file of old thefts, which Bottando had a theory about - that they might all have been the work of one mastermind, nicknamed 'Giotto' - in order to prove his point. But, coincidentally, at this point Flavia and her boyfriend Jonathan come across evidence regarding one of these thefts which seems to indicate that Bottando's wild theory might have had something to it after all. But can they turn up enough evidence in time to vindicate Bottando?
See review for the whole series under "The Immaculate Deception" by the same author.