This fifth book in the Marshal Guarnaccia series takes our hero from the streets of Florence, his usual haunt, and into the countryside on the trail of a young Swiss art student who has disappeared. The Columbo of Italy, Nabb's likeable Guarnaccia is not entirely at ease, a Sicilian living in Florence, but he's deceptively clever (and a solid citizen).  (ITL640, $12.00)