In northern Italy, in the Brescia Province of Lombardy, lies a fountain of youth. The fresh winds blowing in off the Alps have something to do with it; the lake, too, the way it stretches down from the mountains like a shimmering green tail.

Polished mahogany speedboats glint across the surface, skimming past bathers cooling off along the shore—a scene from The Talented Mr. Ripley were it not for the noticeable lack of Hollywood here. There’s little glitz, no remnant aristocracy. What the villages cradling Lake Iseo have are vineyards, lots and lots of them, and a young, well-heeled wine trail luring Champagne-tier oenophiles from all over Europe.