DAWN breaks over the castle-studded skyline of Piemonte. The cloudless north Italian sky is a perfect blue, the air is crisp, a heavy dew lies on the nebbillo vines and forests of oak, poplar and willow. Furtive figures glide through the mists that cover the valley floor. Umberto Bombana strides to keep up with Dick, a scruffy brown-and-white hound of uncertain ancestry. Dick's owner, Luigi Viberti, has already crested the next rise and looks down on a promising glade where oaks sweep into a messy embankment of tangled blackberries and wild mint. He whistles and Dick hurls himself into the brambles. It is a typical partnership among the truffle-hunters of Piemonte, the world's leading source of the buried fungus. Mr Viberti, a retired postman, has been truffle-hunting for 70 of his 77 years. He is the brains of the team. Dick is the nose, possessor of a phenomenal sense of smell that can sniff out the unique odour of the elusive mould up to a metre under the soil of Barolo and surrounding areas of Piemonte. Mr Bombana, chef of Toscana at Hong Kong's Ritz-Carlton Hotel, is on his first truffle expedition, seeking raw material for a Piemonte food festival planned for the end of the year. Ugo Alciati, chef at the Michelin two-star Guido restaurant in the Alban hills, will also be cooking at the hotel's New Year's Eve dinner: truffles are on the menu. Throughout these hills, hundreds of men and dogs are seeking the aromatic underground mushrooms. It is a quest that has been going on for thousands of years. Long before the rise of the Roman Empire, local farmers looked forward to autumn; after the harvests were reaped and stored, the truffles started sprouting. In the provincial town of Alba, which is also capital of the barola wine region, truffles are a major industry. In Via Victor Emmanuel II, the tourist-clogged main street of the old city, choice white truffles cost $25,000 a kilogram. Every October, truffle mania sweeps Piemonte. Hundreds of thousands of normally sane people begin sniffing the air, and stray mongrels, like Dick, are eagerly taken home off the streets. Until a few years ago, there used to be a truffle dog university up the road in the town of Roddi, where a hardened old truffle-hunter would educate mutts to sniff out the fungus. Mongrels are preferred for the work. Mr Viberti explains they are desperate and keen to work. Training is based on hunger. The dogs are not fed until they sniff a hidden truffle and start to scratch it out. The master then delicately prises open the hard earth with his narrow-bladed adze, digging until he finds the tough, fibrous ball. To the uninitiated, a newly dug white truffle does little to excite. They look like misshapen new potatoes, bulbous and wrinkled. To Mr Bombana, however, these are nature's supreme gift to the culinary arts. 'The Mozart of mushrooms,' chefs proclaim. Peasants in these mountains prized truffles when Julius Caesar was a boy. But it was only in 1903 when Victor Emmanuel III visited the Alba annual agricultural show (wine, fat sausages and truffles, what more do you want?) that the modern era began. By 1932, special trains from all over Europe were heading for Alba. Today, they come by jet to Milan, then two hours on the autostrada. The hotels are filled. Every restaurant offers truffle menus. The distinctive aroma wafts down the medieval streets and into the cathedral. In autumn in Alba, they are mad about mushrooms. Every Saturday and Sunday from September to January, the public truffle market is set up in a huge canvas marquee just off the main street. In the culinary boutiques, alongside the elegant designer clothes shops and the outlets for Italy's most expensive wines, cleaned truffles and prepared purees and oils are sold. In the tent, the raw-boned and hardened truffle-hunters are down from the hills to sell their harvests. Some, like Flavio Bordizzo, work most of the year at jobs like painting houses. Others are school teachers, mechanics or, like Mr Viberti, are retired. When the truffles start to swell from the spores in autumn, they quit their normal pastimes, grab their adzes, untie their mutts and head for the hills. Mr Bordizzo's stall in the truffle market had subterranean mushrooms he had dug up during the week worth about $60,000. Chefs come from all over Europe to the truffle show; prices are more reasonable and you can see exactly what you are buying. Buyers hold the vegetables under their noses, taking long sniffs. Like fine wine, they contend, you can tell by the smell what region, what earth, the truffles come from. In October, the rich aroma wafts over Alba and other towns in the truffle belt that stretches over northern Italy and into France. But Alba is the acknowledged truffle capital. Just after dawn, Mr Bombana and Mr Viberti sprawled companionably under an oak tree, looking across the vineyards and orchards of the Barolo wine region towards the impressive mansion of Frontanafredda estate. It was in that winery that Italy's first king, Victor Emmanuel, installed his mistress, keeping up his strength with copious amounts of red wine and dishes like quail eggs topped with generous slices of raw truffle. Myths and lore about the fungus fill scores of books. According to Mr Viberti, whose ancestors have dug truffles long before Christopher Columbus learned to sail, the pull of the moon influences growth. Some say truffles grow where lightning strikes. Some say the ground must be damp, others dry. There are the oak tree school of persuasion and those who hold that linden roots attract the spore. Everyone, however, agrees with the Romans: there is definitely an aphrodisiac quality. Year after year, truffles appear around the roots of the same oak or willow trees or on the same patch of land. Nobody knows why. No scientist has ever been able to cultivate this most stubborn of fungi, although attempts have been made by agronomists in China, New Zealand, Argentina and Canada. After three hours of trekking through muddy streams, sunny vineyards and shaded glades, Mr Viberti, Mr Bombana and Dick have managed to unearth two truffles. One is the size of a small matchbox. The other looks like a dried prune. Both men are ecstatic and Dick, who has also caught a field mouse and run off with Mr Bombana's camera, has got his reward in the form of frequent snacks of hard, tasty dried farmhouse bread. But Mr Bombana needs more fungi for his promotion, so he heads to the market. One prize up for sale is a knobbly apple-sized truffle with an asking price of two million lira (about HK$10,000). Wisely, Mr Bombana has done a private deal with a wine-maker, Gianni Galiardo, who has passed the word to truffle-hunters who dig around his winery on the flanks of La Morro mountain. So Mr Bombana gets first choice of selecting what he wants: the $40,000 he spends gets him sufficient truffles to vacuum-pack into a container for him to carry back to Hong Kong. 'A very good price,' he says contentedly, his nose buried in the mound of mushrooms.