he monastery of San Giovanni has few treasures -- only a painting doubtfully attributed to Caravaggio. So Flavia di Stefano of Rome's Art Squad is surprised to receive a tip-off that a raid is being planned. The raid happens, but the thieves are disturbed and snatch the wrong painting, a curious icon of the Madonna, remarkable only for the affection in which it is held by the local population. Or is this what the thieves wanted all along? Does the...