The bus churns to a stop in Lamego. I grab my bags and fly out the door into the back of an idling cab. “To Carnaval!” I cry.

Shaken from his afternoon paper, the driver springs into action, hits the gas, and careers into the countryside. I left Lisbon this morning for Portugal's northern interior, and the surrounding snowcapped peaks are already turning blue in the fading light.

“This is the last day, no?” His questioning eyes meet mine in the rear-view mirror. I'm grateful for his good English, but he's mistaken: though formalities began weeks ago, for me Carnaval's just starting.

We race past orchards and monastery ruins, hashing out a plan. He drops me off on the road to Lazarim, where festivities are under way.

The Largo do Padrí£o is thick with spectators. Twin oxen, their massive heads crowned with flowers, pull a cart of waving children across the cobblestones. Shawl-draped women strut in lock step, harmonizing folksongs. Packs of agile dogs dart through the drummers and fiddlers, circling carts where fat slabs of dried pork hang just out of their reach. There's not a scantily clad samba dancer in sight. What sort of Carnaval is this?

In the 15th century, Portugal navigated its way into the earth's far corners, bringing along its language, architecture, and music, and the Christian calendar. Its largest colony, Brazil, grew with the West African slave trade. The resulting commingled culture adopted the Portuguese Entrudo (or Fat Tuesday, the day before Lent) and over time infused it with a riotous, licentious joy.

Carnivals worldwide borrow those joyous rituals from Rio. But in the untouristed, terraced hills of the Alto Douro, customs more consistent with Portugal's Celtic origins hold sway. Here, the Lenten calendar is intertwined with the harvest cycle and Entrudo brings parody, poetry, and the purging of winter.

Preparations begin in January, when the social hierarchy is tested. The women serve the men peasant fare as a sort of putdown. Meanwhile, key players are chosen, money is raised, and os testamentos, the rhyming verse and centrepiece of Entrudo, are written in secret.

I've arrived two days before Entrudo, on Fat Sunday. Venturing past stalls of handicrafts, meats, and cheeses, I enter a voluminous white tent. In the bright afternoon light, long tables are set family-style, with fresh bouquets, commemorative plates, and schedules of events. Townsfolk scurry about, hefting hunks of rustic bread and trays of meats for the grill. Vinho tinto flows freely as dignitaries and celebrants embrace through nubby woollen coats.

Inside the mask makers' workshop, three men hack into slabs of alder; chips fly into the frosty air and land in fragrant piles. The partially etched features of a skull, devil, and deer await refinement. Such masks have long played a role in Carnaval, and the instant anonymity they give may inspire nefarious deeds.

With the sun moving behind the mountains, the chill intensifies. After feasting and merrymaking, there's an exodus to local inns for the night. Under starlight, I backtrack along the frozen rutted road, spot the warm yellow headlights of my cab, and fall into the back seat for the return to Lamego.

Fat Tuesday begins with ominous clouds threatening rain. The curious return undeterred, and a television crew from Lisbon runs cables and positions cameras. For the first time, Lazarim will be included in a national Carnaval roundup, set for broadcast that evening.

Tangy aromas lure us to a group of sturdy women arched possessively over bubbling iron pots stirring feijoada with determination. Flushed and grimacing, they shoo away children who dart about the edge of the fires like fairies.

There's warmth in the crush of people. Despite prodigious consumption of spirits, the atmosphere feels civil, almost restrained. Perhaps it's too cold to make real trouble.

“Madre de Deus—o sol!” A squinting, black-clad matriarch points to the sun, which has shifted from behind the clouds to brighten the landscape. And now the first devil appears. Inscrutably masked, suited in straw, he pierces the sky with a wooden pitchfork and forges a path right through us.

Entrudo has begun.

A moon-masked marauder on a donkey, a maiden shrouded in lace and ivy, and a cross-dressing, umbrella-toting phantom materialize. Geishas, goblins, and long-tongued demons pop up abruptly and, in an ancient Carnaval tradition, of ritualized aggression, douse spectators with clouds of cornmeal and disappear. Fidel Castro, Osama bin Laden, and Portugal's legendary poet Luis de Camíµes are among us. A pope draped in a woven flea-market rug blesses all with his sceptre.

Later, we thread our way back to the main square and pack in, awaiting the featured event. All eyes are on a balcony above, where a young couple in funereal garb stand poised, books in hand, framed by swaying, colourful male and female effigies held aloft on sticks.

All fall silent for the “testaments of the compadres and comadres ”. These rhymes, which tease, chastise, and judge, are the will of the town elders, whose impending mock sacrifice is symbolic of renewal. Each four-line verse is punctuated by a drum roll, laughter, and commentary from the crowd.

Squeezed between a masked sheep and a skeleton, I feel like a visitor at an extended family gathering. My Portuguese is poor; I miss some punch lines and just revel in the rhythm.

After hours of recitation, there's a palpable release as the readers close their books and descend the stairs. Cigarettes dangling from their lips, the drummers begin a dirge. The readers lead a procession of bobbing effigies and assorted devils, animals, politicians, ghouls, and spectators.

We wend along ancient granite paths to where Lazarim backs into the mountains. With great theatrics, the effigies are carried uphill to a platform and then lit with torches. Like an amusement-park attraction, they whistle and whirl in circles before exploding in puffs of coloured smoke.

Amid cheers we reverse direction and mischief resumes: more dousing, rambunctious running, and the occasional lecherous prod. Through amused villagers' half-open gates, I spot fruit trees, small vineyards, and lines of laundry dancing in the smoky air.

With dusk's closing ceremony, participants are recognized for distinctive costumes or masks, which are then removed with great flourishes: that menacing red devil is a sweet-faced student, the moon-masked donkey rider actually a grape harvester.

The party is hard to leave. Hands cupping empty bowls, we amble back to the cozinheiras, guardians of the pots. As they ladle out their steamy concoction, we slurp, chat, and mingle by the embers, now the sole source of light.

When I return to Lamego, I dust the cornmeal from my clothes, shower, and settle under the covers with the remote control. After the late news, Portugal's Carnaval cities report in: Torres Vedras, Ovar, Loulé. Amid all the giant comic floats, huge crowds, and glittery samba dancers, Lazarim stands out. On-screen, it appears even more rustic, the masks even more cryptic. I feel like a time traveller, safely returned.

ACCESS: Fly into Porto, Portugal's second-largest city, and rent a car at the airport for the 90-minute drive to Lamego. It's 15 minutes further to Lazarim.

Several country inns offer special packages. Try Quinta do Terreiro ( www.geocities.com/quintadoter reiro/ ), Hotel Rural Casa dos Viscondes da Várzea ( www.hotelruralviscondesvarzea.com/ ), or Casa de Santo António de Britiande ( www.casastoantoniobritiande.com/ ) .