By its cover

When several valuable antiquarian books go missing from a prestigious library in the heart of Venice, Commissario Brunetti is immediately called to the scene. The staff suspect an American researcher has stolen them, but for Brunetti something doesn't quite add up. Taking on the case, the Commissario begins to seek information about some of the library's regulars, such as the ex-priest Franchini, a passionate reader of ancient Christian literature, and Contessa Morosini-Albani, the library's chief donor, and comes to the conclusion that the thief could not have acted alone.