DOURÉ IS STRIDING along the edge of the escarpment, a thin figure silhouetted against the lavender dawn. He is nimble, his pace swift and economical. A Kalashnikov is slung from one shoulder, carried easily, almost as though it were not real. The path arcs along the curve of the precipice, a 3,000-foot drop just inches away, but Douré is surefooted, singing quietly, insouciant. This dry, deeply riven country is his homeland. We are hiking through the Simen Mountains of northern Ethiopia. Douré, our armed scout, is out in front, followed by Mulat, our guide; Sue, my wife; and me.

The first look over the escarpment, even if one is accustomed to the vertigo of mountains, is shocking. In a nanosecond the eyes gauge the fantastic drop, the mind imagines the plummet to death, instinct secretes a warning into the blood, and the body recoils.

There are chasms of air beside us. The scalloped rim presents a series of sheer walls ahead and behind, but to our left there is an utter falling away, a dropping and dropping until a dissected badlands finally looms up. The black shadow of the escarpment cuts jaggedly across this netherworld far below.

“It's like the Grand Canyon,” says Sue. “Like looking off the South Rim without a North Rim on the other side.”

Douré and Mulat stop and pass the binoculars back and forth, glassing the walls. They are searching for ibex. They find nothing, and we continue along the escarpment. The trail drops down a hundred feet, paralleling the scythelike curve of the canyon rim, and then begins ascending.

There's something ahead of us on the trail: a shaggy mane silhouetted against the skyline.

“Lion baboon,” Mulat whispers.

We move forward in a crouch, halting behind a bush. It is a troop of baboons, perhaps 50 in all. They are warming themselves in the morning sun, picking lice from one another's fur, cavorting, chewing grass.

“Gelada baboons,” Mulat explains. “We name them lion baboons, or bleeding hearts.”

The males have great lionlike manes of tawny fur. “Bleeding heart” refers to a distinctive triangle of bare pink flesh on the chests of both males and females. Unlike some African baboons, these lion baboons are afraid of humans. As soon as Sue and I try to approach, the dominant males curl their lips back and bare their teeth. We immediately freeze, but now they are agitated. The big males are nervously cocking their heads. They begin to scream. It's a signal: Suddenly every animal in the troop flies to the edge of the precipice and flings itself off.

We're stunned. It seems they have committed suicide en masse. I spring to the edge, drop to my hands and knees, and peer over the rim. I expect to see several dozen primates flailing down through thin air.

Instead, they are all perched on tiny ledges along the sheer face of the cliff. I can't understand how they have landed safely. Then one of the baboons spots my white face. Shrieks echo along the rock and the entire troop leaps into space, allowing itself a free fall of ten or 20 feet before reaching out impossibly powerful hands, grabbing hold of tufts of grass, and gracefully swinging itself back into the cliff. It is the most dazzling display of agility and sangfroid I have ever seen.

THE SIMEN MOUNTAINS stretch from east to west across the far north of Ethiopia, 75 miles south of Eritrea, 100 miles east of Sudan, 350 miles west of the Red Sea. The range is actually a wildly incised plateau with a vertical, north-facing escarpment.

The Simens have had a battlement view of the interminable war between Ethiopia and Eritrea. In 1962 Ethiopia attempted to absorb Eritrea, precipitating a 31-year civil war. Although Eritrea eventually prevailed, declaring itself an independent state in 1993, sporadic fighting continued. Last July a cease-fire was negotiated, and in December, Eritrea and Ethiopia finally signed a peace treaty that may endure.

Since working as a newspaper reporter in Kenya in the mideighties, I'd been dreaming of a trek in northern Ethiopia. For the Simen Mountains are not only home to an amazing landscape and an ancient enclave of Amhara farmers, but they are also one of the last pinpricks of habitat left for three endangered mammals: the gelada baboon, the walia ibex, and the Simen wolf.

Gelada baboons and their relatives once roamed the African savanna from Ethiopia south to the Cape; today they live only in the Afro-alpine ecological zone of Ethiopia. They are the only primates in the world that subsist on grass, and they have the greatest manual dexterity of any monkey on earth.

The walia ibex exist only in or near the miniature (69-square-mile) Simen Mountains National Park. The walls of the escarpment are their final redoubt. At last count, only about 400 animals remain.

As for the Simen wolf, it is one of the rarest and most endangered canids on the planet. There are none in captivity; the total population in the wild is less than 500. No more than 50 and possibly far fewer individuals survive in their namesake range.

The spillover effects of war, coupled with overpopulation, disease, and poverty—the Four Horsemen of the Apocalypse that have ravaged so much of Africa—have left the wildlife in the Simen Mountains balanced on the brink of oblivion. In 1996, the United Nations designated the park as an endangered World Heritage Site, and it is one of the precious few places on the planet that desperately need foreign visitors—their money and their encouragement.

A month after the peace treaty was signed, Sue and I flew to Ethiopia.

WE ARRIVED IN THE dusty village of Debark after two days of flights and four hours in a grinding local bus. The headquarters of Simen Mountains National Park is a tin-roofed bungalow on a steep hillside.

The cost for a week of trekking in the park for two hikers—plus a scout, a guide, a muleteer, and two pack animals (all mandatory)—was roughly $200. An hour after we paid, our packs were already cinched onto two small, slight horses; our white-turbaned mule-skinner-cum-holy-man had murmured prayers for the safety of our journey; Mulat had filled his army canteen with water; Douré had filled his clip with 30 shiny bullets; and we were off.

The trail sliced up through an erosional landscape of mesas and deep gorges where the bird life was stunning.

“Over 830 species in Ethiopia,” said Mulat, “Sixteen endemic to only Ethiopia, 14 endemic to Ethiopia and Eritrea.”

Mulat could name every bird we encountered: red-winged starling, blackheaded siskin, kestrel, white-backed vulture, thick-billed raven. There was an enormous, rufous-colored, sharp-winged raptor circling above us. I pointed up at it.

“The lammergeier,” Mulat said gravely. “The bone bird.”

The lammergeier is a mythic creature to Ethiopians, for it feeds on marrow. Living on the edge of precipices, it will raise skeletons high into the sky, dash them onto the rocks, and then extract the marrow with its curved beak. Legend has it that the lammergeier will sometimes dive at animals, even humans, trying to scare them into falling off the escarpment.

While I walked with Mulat, Sue walked with Douré. The two of them developed an immediate, intuitive rapport. Because Douré did not speak a word of English, Sue practiced her fledgling Amharic.

“Dehna-neh, Douré?” How are you, Douré?

Douré's regal face, very small and chiseled and refined, with pointed cheekbones, a prince's nose, and topped by a purple skullcap, crinkled in delight. “Dehna!” I am fine. He had the highest voice of any man I'd ever met.

I asked Mulat why Douré carried a machine gun.

“For protection,” said Mulat.

“From what?”

“Animals.”

“What animals?”

“Leopards,” said Mulat.

“Leopards don't attack grown humans,” I argued.

“Hyenas.”

“Hyenas don't attack humans.”

“OK. Humans,” Mulat said finally. “Humans do attack humans.”

Who? Rebels left over from the war with Eritrea? Bandits? Opportunists? I was unsure what he meant.

“Are there people in this park who would attack us?”

“No.”

“Then why are we required to hire an armed guard?”

“For protection.”

THERE WAS NO EASING into this trek. In four hours we covered 12 miles and gained 3,000 feet. Much of the land was intensely cultivated, a dry quiltwork of barley fields and hayfields and pastures shorn down to the dirt by goats and sheep. When Simen Mountains National Park was established, in 1969, the region was populated, the plateau thoroughly agrarian. Only the face of the escarpment was free of humans. Encroachment by farmers and livestock was already decimating the park's wildlife. Still, local men were given the opportunity to work for the park as scouts. Some of their families had lived here for 2,000 years; this was their habitat as well.

We met shepherds and farmers, their knobby-kneed legs hardly thicker than their canes, on every slope. Douré greeted all of them. They were his neighbors and we shook their hands. We reached the lip of the escarpment at dusk and camped.

The next morning we encountered the flying-trapeze troop of lion baboons. They made such an impression on Sue and me that, while the muleteer and packhorses beelined for the next camp through the tilled fields, we insisted that the four of us hike along the escarpment for the rest of the journey. Because of the denticulated architecture of the rim, with its numerous and perilous lookouts, this would add countless miles to our trip.

Douré was silently skeptical. No ferenge (Amharic for “gringo”) had ever walked the rim. That trail was for the wild animals, and the locals, people who knew how to walk. But by the third day we had proven ourselves.

There is one sure way to gain the respect of a village African: Walk with him. NGO workers are chauffeured around in white Land Cruisers. Soldiers roar by in military trucks. The untouchably wealthy blacks and Indians cruise past in Mercedes sedans with tinted windows. But rural Africans walk. Their legs are their life. You can give them food or money or praise or pity and you will hardly get a thank-you. But just once, step out of your automobile and volunteer to walk with them, at their pace for as long as they walk and as far as they walk, without whining or judging or condescending, and you have earned their respect for life.

Ethiopians go only by first names, which often have meaning. Tesfaye means “Hope.” Terunesh means “Wonderful.” Ababa, “Flower.” Halfway through our trek, Douré rechristened Sue “Madame Gobez.” Madame Strong.

I WAS THE FIRST TO spot the walia ibex. We had left camp before it was light and hiked out to a point called Imet Gogo, the Great Cliff. It is a blade of rock that glides straight out into nothingness. In places it is no more that three feet wide: Imagine a long, narrow diving board sticking out from the summit of El Capitan. We cautiously tiptoed to the end and sat down.

We were inside the dawn. The radiating purples and pinks and oranges were not over there, on the horizon, but all around us. We could stick a hand out into it as if the sky were liquid.

I wouldn't have seen them without my monocular—a group of four, one male, with the distinctively tall, black, backward-arching horns, and three females. They had intelligent faces, dark-brown coats, and white socks. They were skipping along a sheer face, occasionally jumping into space and landing perfectly on a lower ledge. It didn't seem possible.

They were masterful, almost gay, in their footwork. Springing up or down, trotting along rope-thin trails, wheeling and knocking heads with each other. Performing without a net and never with less than a thousand-foot death sentence for one mistake.

We watched them, spellbound, until they disappeared around a buttress. Like the baboons, the ibex had somehow learned to defy the odds. We saw three more bands of walia ibex that day, the last of which was so close we could watch their playful bounding with the naked eye.

THE LAST NIGHT, we camped outside a village called Gich, a collection of round thatched huts. This was where Douré had been born and raised and where he lived today. Each hut was surrounded by an intricate brush wall. Inside the wall was a carefully tended vegetable garden and a few head-snapping chickens.

We put up our tents and Mulat started a small fire. Just after dark an old woman hobbled into our camp. She had gashed her leg splitting firewood. By firelight, Sue cleaned the wound and I dressed it. We gave her antiseptic cream and painkillers and she vanished back into the dark.

“That was good of you,” Mulat said. “It was not bad wound, but she is old.”

“It was pretty deep.”

Mulat shook his head. “That is not deep.”

Then Mulat told me how he had been taken from his home by henchmen of the Mengistu regime, beaten, and sent to the Eritrean front. He had survived three years in the trenches. He was only released after being wounded in the leg by shrapnel.

“It was very, very, very bad,” he said.

“Did you have friends die?”

“Many, many, so many. It is normal in Ethiopia. In Ethiopia, if you are in army, you die.”

“Somehow, you didn't.”

Mulat shrugged.

Some minutes later, he said: “It is better to die than be forever damaged. Then you only suffer once.”

That evening, Douré invited Sue and me into his tiny mud hut for dinner. We sat around a flickering fire on goat skins in the smoky near dark. He introduced us to his wife, Taggusunnat—Patience.” She was squatting by the fire wrapped in scarlet cloth, her shoulders draped in a soiled blanket. She was young, with a tattoo of a cross on her right temple and lustrous brown eyes. She shook our hands with both of hers.

We had injera and coffee. Injera is the Ethiopian staple, a platter-size crepe made from teff, a grain similar to couscous. (And coffee, of course, is native to Ethiopia; the word may have derived from the ancient southwestern province of Kefa.) Douré tore off chunks of mud-colored injera while Taggusunnat poured cup after cup of high-octane coffee.

We talked with the help of sign language. Douré is 42. Until the age of 30, he went barefoot. Now, as a scout, he wears plastic sandals. He carries no backpack and wears the same jacket in all weather. He carries no water and only a chunk of bread in his pocket for lunch. He carries the AK-47 but has never fired it. He has never been sent to war. He has never been sick. The Four Horsemen have not yet found him hiding high in the Simens.

That night, lying in our sleeping bags, Sue and I heard the ululating of the women of Gich, a celebration of some unknown event in the life of the village. The joyful trilling rose and dipped and rose again.

DOURÉ IS STRIDING along the escarpment through a lavender dawn. It is the last day of our trek. The trail moves in a straight line down through rocks and across incipient wadis. The stars are vanishing, details in the rugged landscape resurfacing from the depth of night. Douré is humming, Sue and Mulat silent.

We are moving in single file at a distance-devouring clip. Douré's eyes are scanning the horizon when he abruptly stops. His small head spins sideways. “Ky kebero!” he whispers, his voice as high-pitched as a girl's. A wolf.

I try to look precisely where he is looking but see nothing. Mulat spots it and points.

Douré swiftly pulls a pair of binoculars from his pocket and hands them to me. I pan, stop, back up to a flicker of motion.

“What is it?” Sue asks.

I see it now. “A wolf!”

The wolf is loping across the plateau, head down, moving quickly. It is an ephemeral figure, more the size of a jackal than a wolf. Reddish fur with flicking white socks. It bounds over the frosted grass, weaves through the giant lobelia.

I pass the binoculars to Sue.

“Where?”

“Ten o'clock.”

She scans the exact place but sees nothing.

“I am sorry,” says Mulat, “Ky kebero gone now.”

Suddenly I remember. I'd heard them last night.

At first the distant yipping and howling had been in my dreams; beginning to wake, I'd thought I invented it. That is what you can do in dreams—create a world you wish existed. But then the choral yelping had separated from the hypnopompic images and I'd realized that the singing was real, echoing in the surrounding darkness.

I'd pulled my arm out of the warm sleeping bag and pressed the light on my watch. Four-fifteen. I'd lain back and listened. The faint call and response and refrain, like a faraway psalmody in some ancient language, had cheered me immensely. Somehow, despite everything, they were still alive. They were out there, even if we never saw them.

Bleeding Hearts