This place we had come to in deepening dusk, shivering in our too-thin clothing, was a frozen, treeless, shrubless high plateau. Standing by the jeep, we two westerners felt a momentary kinship with those who climb high mountains and explore continents. Then all five of us were grinning foolishly at each other and jumping up and down to keep warm. On this late October day we had reached the marker that divides Pakistan from China at the Kunjirap Pass, nearly 16,000 feet high.

We had not intended to go to China, my son Ted and I. The original focus of our trip was India and Nepal -- surely a rich enough double lode for us to mine in 10 weeks of projected travel. But once in the area we were infected with a powerful urge to travel farther, and had come to Pakistan just a few weeks into our trip. Now, on what must be labeled impulse, we had arrived at this unlikely place -- the most northern outpost of the country, its border with China.

So inhospitable a spot was this that the last military posts of the two nations were 50 miles north and south of this border. We had met only six automobiles and trucks in the hour and a half since the check post.

Without impediment, we ran 50 yards into forbidden China, which, until six months before, had not permitted any western travelers to pass this way. Then, lightheaded from the altitude and very cold, we climbed back into the canvas-covered jeep and prepared to make the return trip to the village of Gilgit in the dark.

Only a day before, we had gone through the lengthy, body-patting security check at Rawalpindi in Pakistan and flown over the lower Himalayas and the Karakorams and into the Gilgit Valley, in the far northern reaches of Pakistan. Once we were underway on that bright day, we found out our windows one of the world's spectacular air views, on a flight costing less than $20 round trip. Gradually the lower range gave way to thrusting peaks. Nanga Parbat, "The Naked Lady," ninth highest mountain in the world, revealed itself vast and recumbent to the east. For 10 transfixing minutes we moved past this killer mountain, which has claimed so many lives.

The town of Gilgit, 5,000 feet high, showed itself almost immediately to be a rough-and-ready place, with crowded bazaars and a noisy frontier outpost's bustling energy. To the north lay the Hunza Valley, which had been closed until three years ago to foreigners who wished to travel beyond its capital, Karimabad, just 60 miles away from Gilgit. The valley, surrounded by enormous mountain walls, had only become known to westerners generally in the mid-19th century.

To drive through this beautiful valley, purportedly the Shangri-La of James Hilton's "Lost Horizon," was our modest aim. But no sooner had we settled into the Chinar Inn in Gilgit than we met two other Americans and everything changed. We talked to a Texas couple who had just made a five-day circuit into China by hired auto. Adventurous travelers, they spoke of the drive and the experience with exceptional fervor: "Nothing like it anywhere," they insisted. Ted and I began to rethink our agenda.

Travel in Pakistan generally is a bargain, with first-class hotels at about $35 per night double and others for as little as $10. But jeep travel at 6 rupees a mile (the exchange rate was 17 rupees to the dollar) was not cheap, and the fee was "not negotiable," as we heard from all sides. The round trip to China wouldn't fit our budget.

However, Asif Khan, director of tourism for Hunza, was on his way to Karimabad when we saw him at 7the next morning. "Want a ride?" he asked. Within a few minutes, we were having our first experience of the Karakoram Highway as we passed over a two-plank suspension bridge and into a tunnel. Almost cylindrical, and designed for one vehicle, the tunnel seemed to have been gouged out of the granite cliff by a giant pencil.

The Karakoram Highway -- an evocative name and a formidable reality. Begun in 1965 as a two-lane highway designed to carry heavy traffic from Gilgit to the Xinjiang Province of China, it was 15 years in the building and blasted out of the towering cliffs, a marvel of engineering that the two nations are prone to claim as the eighth wonder of the world. It was built at the cost of many Chinese and Pakistani lives: The official figure is 408, the unofficial far more.

Asif was running late. Glancing occasionally at his watch, he drove with concentration on the narrow, precipitous road. The cliff dropped dizzyingly off to our left.

The Silk Route, by which the merchants of Asia had carried goods and spices to the subcontinent for hundreds of years, at first wound tortuously along the opposite wall of the valley. Sometimes our track was superimposed upon that well-trodden path; at other times we could see it snaking along separately. I imagined loaded donkeys and camels and laden men, and the occasional thrashing horror of a wheel or a foot over the edge and the shrieking, crashing plunge into the valley below.

It was a smiling valley under the sunshine of this day. The storied Shangri-La was the hidden civilization whose people, looking forever young, reached immense old age. There below us at this moment were the apricot and apple orchards that, together with good habits and the rarefied air, purportedly made the people long-lived. Beside the flowing Hunza River were poplar, willow and chinar trees. A little higher were tawny cornfields in terraced gardens and, far above, the mountains.

Presently we were to see the people of this valley, descendants of migrants from the Pamir Mountains in what is now Soviet-occupied Afghanistan. Their tongue is Brushuski, although here, as across Pakistan, Urdu is the official language. The valley people -- Muslims, like most people of the nation -- are of that minority branch called Ismailis, followers of the Aga Khan. This area was once a center for fairy worship, but the highway is bringing an end to old customs and a melding of local distinctions.

Now we were seeing snow-covered Rakaposhi to the east, another giant towering more than 25,000 feet. Below lay tiered Karimabad, a town of several thousand, where we had thought to wait for events to take their course. But Asif was asking a question: "Would you like to go to Gulmit?" Gulmit, a village of a few hundred people, was 90 minutes north -- closer to China. We could make the round trip to China this very day, perhaps. We said yes.

In fact, Gulmit was Asif's home town, and his father, a hero in the Pakistani-Indian wars and a prominent figure in the area's travel industry, was still the headman of the village. When we reached the village, Asif unloaded us quickly into a dusty street and drove away. But he had arranged for someone to lead us, and presently we found ourselves before a locked gate in a high whitewashed wall. From inside, someone unbolted the gate, and we were standing in the quiet enclosure of the Village Inn. Now a hostelry, this had been the headman's home for a hundred years, the elder Khan later told us. The wall merged into the main building, whitewashed stucco with deeply recessed windows and wooden doors. In the garden stood a separate dwelling housing four "new" bedrooms, dating from the 1950s. Our bedroom was very clean, with warm blankets piled high, an oil lamp and cold water in a separate bathroom.

Passive acquiescence had brought us this far. At this point, we were ready to take action. Could a jeep take us to China today, we asked the manager over tea. He demurred, suggesting by word and gesture that early tomorrow morning was the time to go. We avowed in the same way that we must return to Gilgit tomorrow. It was now or never. In that case, he would arrange it, he indicated, but there were no jeeps here. A jeep must be summoned from Karimabad.

Presently we could hear a shouted telephone conversation between the manager and some listener in the other town. Our acquaintance returned with good news: The jeep would arrive at noon. I calculated rapidly. The trip would take 3 1/2 hours each way, Gulmit to Kunjirap. We would be returning in the dark, but only for an hour or so.

The jeep arrived hours later, at 2 p.m., after a time of anxious waiting for us as our safety margin faded away. We gathered soberly in the dusty street while the driver, Akil Shah -- short, sturdy, graying and severe, clad in a sweater, jerkin and a single glove -- showed by raised voice and vigorous gesture how thoroughly he disapproved of this enterprise. He had expected only to ferry visitors back to Karimabad. He did not have enough petrol to get us to China. Furthermore, we would hardly get to the border before dark. We would be cold. We would not be satisfied. The project was, his chopping motions indicated, absurd.

I looked at the open jeep, its fuel tank strapped behind, at the sun already beginning its western descent. I contemplated a height of 16,000 feet up a serpentine and precipitous road, inadequate clothing and temperatures well below freezing, and hours and hours of descending in the dark, and I agreed with him. I hoped someone would forbid us to go.

My son Ted, however, is 25 years old, and chances to go to the roof of the world come seldom in a lifetime. No one insisted we give up our plan.

In minutes, we were bundled up as well as we could manage and seated in the jeep. We jounced our way out of Gulmit and headed north, picking up fuel on the way.

The jeep appeared to be held together with tape and wire. Akil stopped at intervals to open the hood and sometimes to start the motor with two wires. Once he struck something under the hood several sharp blows with a wrench. After these communings, a faint smile would play about his lips.

In the first five miles we detoured around a landslide mass of boulders and rubble and then pushed through water up to the hubcaps. Very shortly, Ted and I were chilled to the bone.

Presently we came to Sost, one of the military checkpoints, where two mustachioed young men approached our driver. Each was wearing the national garment, a shalwar kamiss, gathered trousers of light fabric and long overshirt, as well as a sweater. Akil made perfunctory, dismissive gestures while one young man inquired of Ted, "May we come?"

The buccaneer appearance of these young men brought lifelong injunctions against picking up hitchhikers to my mind. I turned with a warning look, but the two were already climbing in on either side of Ted. "I'm cold," he explained reasonably.

Within minutes, the young men had identified themselves as Amir Ali, 19, and Lutfullah Khan, 21, both teachers at a nearby village school. "I speak Brushuski, Urdu and broken English," said Amir cheerfully, in answer to my question. He had been to the Chinese border twice, he explained, but his friend had never been. Soon they were both so cold in the open jeep that they were visibly trembling, but their good-humored banter thawed out our frosty driver and warmed us all.

Lufkullah's English was confined to a few laughing words, and Akil the driver's was nonexistent. The three men exchanged local gossip, and occasionally Amir translated. Soon he poked his friend and said smiling, "He is a father." This was true, Lufkullah's proud face told us. His wife, from whom he was separated all the teaching week, looked after their baby in his village. Later we were to learn that such teachers as these young men earn about $80 a month.

It was nearly 4 o'clock when we stopped at the final military checkpoint, consisting of a wooden barrier across the road, a few men in khaki and a low dark hut. As we stepped out of the jeep, Lufkallah and one of the soldiers exclaimed simultaneously and grabbed each other in a joyous embrace. "They are from the same village," Amir explained.

We were led through the hut's low doorway and invited to produce our passports. "We allow no one to go to the pass after 4 o'clock," said a sober-faced man in a heavy jacket. "Why do you wish to go there?" We explained, and he remained quietly thoughtful. In a moment he made notations in his book, smiled at us and motioned to someone in the back of the hut. Suddenly, miraculously, tea in small mugs appeared before us. Now the soldiers in this bleak outpost 12,000 feet high made friendly inquiries, welcoming a variation in their austere routine.

Akil had battened down the jeep under a frayed khaki cover, and the two teachers, wearing borrowed overcoats, were bright faced and ready for the worst when we got underway once more. Ahead of us lay, at best, two hours of daylight and 50 miles of steep highway. This was our race to the top.

Long shadows stretched across the frozen ground with its light snow coating. The sun was no longer visible behind the enormous peaks to the west.

Our road wound up and up and we began to see kilometer signs, 13 k., 10 k., 3 k. We called out the numbers in our various languages. The air was palpably colder. The wind whistled through the canvas. Then the road straightened out and just ahead stood the simple border marker. We were at the top.

Jubilation! We pumped one another's hands and ran wildly, the boys' overcoats flapping, across the border and into China. I felt strangely lightheaded, and at this moment, Ted later told me, his head began to throb. At 16,000 feet our motions had a surreal quality. A bright glow remained in the western sky.

A few minutes were enough. We piled back into the jeep again, Akil put the machine into gear, and we began our headlong descent, now racing the sun and the deepening cold.

Only a few kilometers along the road, Akil stopped the vehicle, turned off the motor, climbed out and raised the hood. He had gone through the motions many times before, but at this moment they seemed especially ominous. There was tension and silence in the jeep. Suddenly the teachers began laughing uncontrollably. Amir managed to ask me, "How like you the Kunjirap now, Madam?"

Banging noises sounded under the hood; Akil closed it and climbed back into the jeep. All of us were silent. The motor started and we resumed our downward plunge. Now it was dark.

Amir translated Akil's account of the first time he had taken visitors, a Pakistani group, to these heights. "All four tires burst," Amir repeated. "They had to spend night on the road. One man weeping, he so cold."

Stones were arranged across the road at the military check post, but our friends again beckoned us into the hut, lit now by a dim oil lamp. This time biscuits came with the tea, and this time it was Akil, insistent, who paid for us all. The soldiers, infected by our exhilaration, were smiling now. They asked more questions of us, and we in turn learned that 25 men manned this lonely northern outpost. One man had been stationed there for 12 years.

After the descent to Sost, it was a straight run to Gulmit. Akil sidetracked a few miles to drop off our two companions on the rutted track that led to their village. We said goodbye to them with real regret.

We came back to the Village Inn in Gulmit about eight hours after we had left.

We were to see our driver once more. Having contracted for a round trip from Karimabad to the Kunjirap, we were entitled to a lift to that lower village, and the next morning we were in the jeep once more.

Akil was inscrutable as ever, but he seemed somehow to have softened in the course of the shared adventure. Apparently he had some special destination for us this morning, for he gave no heed to our tentative queries about a spot where we could get a bus from Karimabad to Gilgit.

Presently, he drew up on a street flanked by narrow shops, left us in the jeep and soon returned with a stranger. Courteously, the new man explained that he would be leaving soon for Gilgit and he would like to give us a lift there, without charge. We were out of the jeep now, beginning to express our thanks, when Akil stepped forward. He had not approved of the expedition, undertaken for who knew what mysterious reasons by these underequipped, spoiled and inexplicable foreigners. But he had responded to the camaraderie that reached across barriers of language, gender, custom and age. Now he was our friend. Smiling broadly, he handed us the gift he had purchased for us, a bag of rosy Hunza apples.

Nancy Osius is a teacher in Severna Park, Md., and a free-lance writer.