The Italians called them "Mud Angels," the young foreigners who came to Florence in 1966 to save the city's treasured art from the Arno's flooded banks. American volunteer Margot Harrington was one of them, finding her niche in the waterlogged library of a Carmelite convent. Within its walls she discovered a priceless Renaissance masterwork: a sensuous volume of sixteen erotic poems and drawings.