European white truffles can sell for as much as $3,600 a pound, making them and their fellow fungi the most expensive food in the world.

Truffles are a fancy, delicious delicacy - some say an aphrodisiac - and, ounce for ounce, the most expensive food in the world. If you go to France and Italy, as we did, you learn quickly that truffles are under siege because they're becoming scarce. They're being trafficked like drugs, stolen by thugs and threatened by inferior imports from China.

In the beautiful Italian province of Perugia, truffle hunters roam the frosty hills with their trained dogs, who sniff out these lumpy mushrooms when they're ripe, one at a time, as they have for centuries.