Picture the scene, if you will. I am spending the night at the remote Refuge de Champoleon, high in the wildest part of the French Alps; the electricity is on the blink, and so the 10 of us who are there -- French, Belgian, Dutch, American -- are dining by candlelight. The atmosphere is intimate; the wine flows.

The conversation turns to jobs and, unexpectedly, one of us turns out to be a professional opera singer -- a tenor from the French provincial city of Besancon. His specialty is Wagner.

"Sing for us; you've got to sing," we cry.

And so he does: Tristan and Siegfried and Lohengrin suddenly leap to life as our tenor stands up, puffs out his chest in the flickering light and bursts into song. The walls of the little hut seem about to explode with rapturous sound.

Outside, a crescent moon comes up over the mountaintops.

Now, picture this. I am struggling up the steep slopes of the nearby Col de la Pisse (8,350 feet) when I hear gunfire. Around a bend in the trail I am confronted by a horde of ghostlike apparitions running full-tilt toward me, whooping and hollering like madmen. It turns out to be a formation of Chasseurs Alpins, France's crack mountain troops, clad head-to-foot in white camouflage uniforms (but highly conspicuous here in the grassy terrain).

The unit comes to an abrupt halt and a mustachioed colonel steps forward: "You shouldn't be here! There should have been notices down the trail. We are on maneuvers."

Lecture over, I am forgiven. With a crisp command, the colonel details two men escort me over the pass. They are polite, but firmly refuse my request for a picture-taking session.

And yet another scene: I am heading up the savage gorge of the torrent of Canteloube, just a few miles from my little Pisse pass, when I hear far above me the sound most dreaded by mountaineers: the clip-clap-clop of falling stones.

I am ready to duck for cover but the clatter is not the beginnings of a rock avalanche. Craning my neck up to the precipices above, I sight the source -- a small herd of chamois, defying gravity, leaping gracefully from crag to crag -- and seemingly alarmed by a solitary hiker hundreds of feet below, namely me! Soon the nimble, sharp-horned antelope are out of sight, hidden by a jutting pinnacle.

In my mind's eye, scene after memorable scene click vividly to life as I recall the two weeks I spent walking the length of one of France's finest long-distance trails -- the Sentier de Grande Randonnee 54, or simply GR54, as it's known to European hikers.

While America pioneered the long trail concept with the 2,000-mile Appalachian Trail, France has perfected it with a wide range of GRs, ranging from easy lowland hikes to tough Alpine paths that pierce the highest mountain ranges. The Paris-based Federation Francais de la Randonnee Pedestre oversees development and maintenance of the nationwide system.

Of all the GRs, 54 is the most difficult. The 150-mile circuit trail, also known as the Tour de l'Oisans, lies in a rugged mountain region east of Grenoble dominated by the great peaks of the Barre des Ecrins (13,455 feet), La Meije (13,065 feet) and Mont Pelvoux (12,900 feet). Twenty other peaks, many of them heavily glaciated, soar to more than 12,000 feet.

By day, GR54 hikers cross high passes, often involving up to 4,000 feet of climb; by night, they sleep in refuges, gi~tes d'e'tape (France's nearest thing to bed-and-breakfasts) or village hotels, where a hot shower is even more welcome than the lavish, four-course dinners that are invariably served.

For Americans, GR54 offers the added enchantment of the unknown: While thousands tread its spectacular terrain each year, the trail is virtually undiscovered territory in this country. Only eight Americans -- yes, eight -- made the circuit in 1988, I was told by refuge guardians along the way.

As one of that rare breed, I was treated (and welcomed hospitably) as an intriguing oddity. "Do Americans really walk?" I was asked, time and again.

Although my hike along GR54 was a solo trek, I was seldom entirely alone and never lonely. Since e'tapes -- day's marches -- between huts are usually spaced to an eight-hour walking day, hikers find they share the same section of trail over a far longer period, and instant friendships develop.

For several days I walked with Jean and Jeanne, youthful grandparents from northern France, and their son and daughter-in-law. Jeanne, with flaxen hair and the lithe body of a 25-year-old, was the leader of their little group and maintained strict discipline on the trail. She was known affectionately as "La Commandante," and read Flaubert at night. Jean, on the other hand, was a joker and kept us laughing with his graphic accounts of the terrible toilets they had encountered in some of the more primitive refuges.

The French family spoke little English, but others did. One was freckle-faced Maja, from the Netherlands, whom we nicknamed the Rocket because she raced off each morning and would be waiting for us at the next refuge, sleek and well-groomed, while we slogged in, tired and sweaty, late in the day.

Then there was Rosemary, a Canadian walking with her English boyfriend, who had aspirations as a writer. And dour Jamie, from Scotland, who -- like many of his countrymen -- was not a devoted fan of British Prime Minister Margaret Thatcher.

One great joy of hiking GR54 is the almost total absence of commercial exploitation. There are no cable cars agog with gaping tourists, no pizza parlors, no junk shops selling tawdry souvenirs. The valleys are much as they were a century ago. Cows, sheep and hens roam the village streets; old women sit sunning themselves outside their cottages; farmers still scythe their fields.

The region hasn't changed much since 1871 when Edward Whymper, British conqueror of the Barre des Ecrins and later of the Matterhorn, wrote in his classic, "Scrambles Amongst The Alps": "Its cliffs, torrents and gorges are unsurpassed; its deep and savage valleys present pictures of grandeur, and even sublimity, and it is second to none in the boldness of its mountain forms."

A major reason for GR54's sense of true wilderness is that much of it traverses the National Park des Ecrins, France's largest at 230,000 acres. The park was established quite recently (1973), but large segments of it have been protected for the past 75 years by various government edicts.

Although the United States was the first to set up a national park, the French are no slouches when it comes to preserving their natural heritage, and some of their park regulations are more stringent than those in this country.

In the Des Ecrins park, all camping is forbidden; bivouac tenting is "tolerated" only in emergency situations, and even then the tent must be located at least one hour's walk from the nearest mountain refuge or two hours from the nearest park access. Fires also are banned.

In addition, the park outlaws dogs, even leashed, and it requires all refuse to be carried out, including anything used in the huts. Guns and radios are, of course, taboo. Along the trail, I was also impressed with efforts to prevent hikers from short-cutting switchbacks -- either by rock barriers or by discreet notices stressing the need to prevent erosion.

All of this is considered essential in a park where the vast majority of terrain is above tree line and where delicate Arctic tundra conditions prevail.

The GR54 guidebooks warn that there are four potentially dangerous segments of the trail, all of them high passes and all requiring ice axes and crampons early in the season, when the north slopes are still deep in snow.

The most notorious is the Col de la Muzelle near the end of the circuit. The map I used marks the pass with crosses ("passage dangerous"); the French guidebook talks of a tricky couloir (gully) to surmount; the British guidebook, with typical dry humor, says the final stage "is without grip ... but, in fairness, you don't see a lot of bodies at the bottom."

Actually, without snow, the Col de la Muzelle proved a snap: steep, arduous, seemingly endless, but never dangerous.

The Col de l'Aup Martin, on the other hand, was something else. The highest pass on the trail (9,250 feet), it was a horror -- mostly black slippery shale and silt, tilted at a 60-degree angle, with rock precipices below and a narrow path that dwindled to mere inches in width as it neared the summit. Nasty.

From a distance, the evil slope looked almost vertical. It didn't help that the weather began to deteriorate as I started the climb, or that I was carrying, in addition to my heavy backpack, a large bag of provisions -- leaving only one hand free for balance and for clutching at handholds if I slipped.

As I neared the col, the mists came down and it started to snow, making the path even more slippery. Step followed narrow step. My legs began to tremble, and soon I was panting, gasping with fear. A slip would have set me tumbling down into the void below. I froze, unable to continue.

I remember feeling stupid and angry with myself as well as scared, wondering how I could have been such a fool as to attempt the pass alone.

But help was at hand. Suddenly, out of the mist, my French friends Jean and Jeanne appeared, rope in hand. They tied me on, grabbed my bag and virtually pulled me up the last treacherous slopes of the pass.

Later, Jean pooh-poohed my suggestion that he might have saved my life. "You wouldn't have died. If you had slipped, the momentum would have been slowed by the weight of your body." I was too relieved to argue the point.

There are 37 refuges in Des Ecrins park, ranging from the palatial to the primitive and, occasionally, to the pits. Many of them are strung along GR54 and each has its own special identity. If you're new to the trail, the only thing you can be sure of is that a surprise awaits at each night's lodgings.

Take the Refuge Gioberney, tucked away at the head of the remote Valgaudemar valley, amid some of the park's loneliest scenery. It's an unlikely setting for this vast, fortresslike structure that can sleep up to 200 in its honeycomb of cell-like rooms and echoing corridors.

The night I spent there, only three of us shared a huge deserted dining room, and we wondered what prompted construction of this monstrosity. The hutkeeper's explanation was as bizarre as the building: It was conceived as a retreat for "tired intellectuals" employed by the collaborationist Vichy government during World War II.

Later that night, the refuge came briefly to swinging life to the strains of rock-and-roll. The longhair musicians looked like '60s hippies but were, in fact, college students letting rip at summer's end before their return to school. They played to an audience of two.

In charming contrast to the giant Gioberney was the tiny Refuge des Souffles, sleeping 10, where the snug dormitory looked like a roost for the chickens kept by Irene, the young hutkeeper.

When I arrived at the refuge, she was cuddling one of her pet hens in her lap and crooning a little tune to it.

"It puts them in the right mood for laying eggs," she explained.

In the winter, Irene worked as a ski instructor and I asked her what would happen to her hens -- would they be "put to the pot?"

"Never, never, never! Absolutely forbidden. They'll go on laying eggs," she insisted.

There were other happy memories to cherish. In that same refuge where our tenor sang, the young guardian, Emile, baked us his special tarte de maison and treated us to Genepi, a subtly flavored liqueur made from wild mountain gentians.

But there was the occasional downer too. I arrived at the Refuge de la Muzelle on a busy climbing weekend to find the hut chockablock with sweaty humanity. My bed was the dining room floor. Hardly had lights been doused for the night than the eager-beaver climbers were up again, beating the dawn by hours. Sleep? Forget it.

There is history galore in these mountains, and a little research digs up some fascinating glimpses from the past. While the peaks are terra incognita to most Americans today, a couple of famous U.S. mountaineers from the 19th century -- the Rev. William Coolidge and his stalwart "aunty," Miss Meta Brevoort -- pioneered many climbs in the area. Together with their amazing dog, a mutt named Tchingel, they made many first ascents around Des Ecrins. (One of the highest peaks in the national park -- the Pic Coolidge (12,700 feet) -- is named after the redoubtable reverend.) Photographs from the 1870s show a stern Coolidge clutching his huge alpenstock alongside a determined-looking Meta, clad in voluminous Victorian skirts that completely hide her feet -- quite a contrast from the brief get-ups that are de rigeur these days for climbers in the French Alps!

Four centuries before Coolidge's exploits, Dauphine -- as the region was then called -- was the scene of one of the most brutal chapters in Christian history.

In the 15th century, Dauphine was settled by a religious sect, the Vaudois, that flouted some of the church's doctrines. Orders were issued to exterminate the heretics; armies were sent in and entire valleys were ruthlessly wiped out. Whymper, in his "Scrambles," tells us that many villagers took refuge in a cave high in the mountains, but were discovered. The army leader "lowered his men by ropes, fired piles of brushwood at the entrance of the cavern, suffocated the majority and slew the remainder." I tried to track down this cavern during my walk along GR54 but no one I met had heard of the massacre, let alone the cave where the butchery took place.

I spent the last days of my trek in the village of La Berarde, which, although some miles away from the GR54 trail, is the focal point of the Des Ecrins massif and superbly situated beneath its highest summits.

The tiny hamlet, at nearly 6,000 feet, shuts down entirely during the winter months, leaving only one man to aid lost cross-country skiers. But in the summer, there are two little inns, one of which -- the Hotel Tairraz -- sports an incongruously chic bar that offers "cocktails" with such unlikely names (in English) as Racer, Wonder Night, Tampico and Exotic Passion.

La Berarde is a famous center for rock climbers but its peaks these days are a nemesis for many of them. In 1988, for the first time, a helicopter was based in the village to rescue injured climbers and made no less than 100 rescue missions during the short climbing season.

The service, operated by the French National Gendarmerie, is wonderfully efficient: Once alerted by radio from a refuge, the helicopter can be at the scene of an accident within 15 minutes. But officials running the rescue operations mourn the needless injuries and loss of life, much of it due to inexperience and macho risk-taking.

In La Berarde, I stayed at a mountaineering center run by the French Alpine Club, which offers precisely the kind of expert training that would prevent climbing accidents. "But these youngsters -- they want to go it alone. They want to prove they are men. They go into the mountains without even basic knowledge and skills, and so they die," I was told.

On my last day, I climbed the little Tete de la Maye, a rocky outcrop above La Berarde that the Michelin guide rightly rates as a three-star viewpoint. It was a perfect ending to my trek: Many of the highest peaks I had seen from a distance over the past two weeks were startlingly at hand, dazzling in the bright sunlight. "Awe-inspiring, breathtaking, stupendous, staggeringly beautiful" -- all the cliches I could think of seemed cliches no longer under the spell of this glittering panorama.

Richard Wightman is a Washington writer. WAYS & MEANS

GETTING THERE: The easiest and most direct way to reach GR54 in southeastern France is to fly to Geneva, served from Washington by several airlines including Pan Am, Lufthansa and British Airways. British Airways is quoting an advance-purchase, round-trip fare of $1,048.

From Geneva, frequent and speedy (about two hours) trains connect with Grenoble, a mountain city well worth an overnight stay. Adjoining the train station is a bus depot with regular scheduled transport to Le Bourg-d'Oisans, jumping-off point for GR54.

WHEN TO GO: The best time is late summer-early fall, when the high passes are free of snow and the huts and villages less crowded than in high summer. (However, some mountain refuges along the trail close for the season in early and mid-September.) In June, and occasionally into July, two of the highest passes on GR54 are likely to be snowbound and could require crampons and ice-ax, plus climbing skills.

MAKING THE TREK: I hiked GR54 on my own, but it is a good idea to take along a pal, partly for the companionship, partly because of the possible dangers and partly for sound financial reasons: Virtually no hotel in these tiny villages provides single accommodation, and you wind up paying for two persons anyway. (Still, most charge less than $30 a night for doubles.)

Group hiking has not yet hit GR54, and I have been able to find only one tour operator who this year is introducing the Tour d'Oisans on an experimental basis. This is the British firm Waymark Holidays (295 Lillie Rd., London SW6 7LL, England), which is quoting 460 pounds (about $830) for a two-week hiking trip, including all meals and transportation from London. The trip is planned for Aug. 12 to 26.

On my late summer hike, accommodations never appeared in short supply and advance reservations weren't needed -- but this situation conceivably could alter drastically in mid-summer.

For the hardy, there are plenty of camping sites in the villages along the trail, although none in Des Ecrins National Park, where all camping is banned except for emergency bivouacs.

MAPS AND GUIDEBOOKS: French maps are among the world's finest and the GR54 is amply served. The Grenoble-based Editions Didier & Richard prints an excellent 1:50,000 map covering the entire route. The Paris-based Institut Geographique National publishes detailed 1:25,000 maps of the area, but you will need three for the GR54.

The IGN also has a 1:100,000 map of the region, which is carried in Washington by the Map Store (1636 I St. NW, Washington, D.C. 20006). The store can order the more detailed maps, but warns of a four- to six-week wait.

In France, you may also buy a so-called Topo Guide of the GR54 trail, with maps and trail descriptions (in French), but I found some of these inaccurate and out-of-date.

The British guidebook "Tour of the Oisans," by Andrew Harper (Cicerone Press, Milnthorpe, Cumbria, England) gives a good blow-by-blow description of the trail.

INFORMATION: Additional tips about walking in France may be obtained from the French Government Tourist Office (628 Fifth Ave., New York, N.Y., 10020, 1-900-420-2003; tourist information costs 50 cents a minute) or from the Comite National des Sentiers de Grande Randonnee (92 Rue de Clignancourt, 75883 Paris, France), the governing body for all of France's long-distance trails.

For great reading, try Edward Whymper's 19th-century classic, "Scrambles Amongst the Alps," on most library bookshelves.

-- Richard Wightman