Formaggio is Sveva Prince's new offering for lovers of mystery novels whose plots unfold in that most bel of all paesi, Italy. The Formaggio Tour ("of Classic Italian Cheeses"), careens on a wild ride from the Italian Riviera to the hinterlands of the Ligurian Alps; from the Italian Lakes Region to fabled southern Tuscany; from charming mountain goat farms to churning vats of industrial gorgonzola. The scenery is great. The food is terrific. The bullets are unexpected. Sybilla Waterman finds she's slinging a cheese knife at a gun fight. Cicerone of Cheese: legitimate job for former architecture grad student at the World's Greatest University? Maybe . . . not. But: Waterman needs to finish something in life, even if it's only a one month cheese tour. Her sister (busy Boston orthopedics practice, devoted husband, four adorable kids) is her underwriter. Sybilla (tiny hovel in Ligurian hills, husband dead 10 years, dog dead one month) has ditched her Brilliant Career. She's lost her Mojo. She needs A Plan. Sybilla and her sister call it "Il Grande Giro Classico dei Formaggi Italiani." Their mother calls it "Syb's Cheese Doodle." "Eat your way through Italy! Learn Little-known Secrets of Italian Cheese!" The Tour Blurb never mentioned careening off the beaten track. Off any track. Getting shot at. Sought by the Carabiniere. Stalked through ancient Tuscan catacombs.The Americans tourists have signed up for different reasons. Unfortunately, some of them are illegal. And something on the bus is starting to smell (hint: it's not just the gorgonzola, forgotten and aging under a seat in the way-back).