In the cabin behind Hosni, Sam and Remi each scooted sideways for a better view out the window. Remi said to Sam, “Eyes open for mushrooms.”

“Aye, Captain.”

Karna’s translation of the cave mural had offered a vague but hopefully useful description of Shangri-La’s most prominent feature: a mushroom-like rock formation. As the mural predated flight, the shape would likely only be recognizable from the ground. Exactly how large the formation was, or whether Shangri-La was supposed to be on it, in it, or simply nearby, the mural didn’t specify. Sam and Remi hoped/assumed that the planners of the Golden Man’s evacuation had chosen a formation large enough to stand out from its neighbors.

In anticipation of numerous landings and takeoffs, they were paying Hosni almost double his usual fee, and had booked him for five days, with a nonrefundable deposit for five more.

The Bell passed over a forested ridge, and Hosni nosed over, descending into the valley below. Three hundred feet over the treetops, he leveled off and decreased his airspeed.

“In the zone now,” he called.

Binoculars raised, Sam and Remi began their scan of the valley. Remi radioed, “Remind me: how accurate did Jack say the coordinates were?”

“Half a kilometer. About a third of a mile.”

“That doesn’t help me.” Though adept at it, Remi was not a fan of math; gauging distances especially vexed her.

“About four hundred fifty yards. Imagine a standard running track.”

“Got it. Imagine it, Sam: that Sentinel was required to hit each of these coordinates almost dead-on.”

“A remarkable bit of orienteering,” Sam agreed. “Karna said it, though: these guys were the equivalent of today’s Green Berets or Navy SEALs. They trained for this their whole lives.”

Hosni flew on, dropping as close to the trees as he dared. The valley, which the Bell traversed from end to end in less than two minutes, yielded nothing. Sam ordered Hosni to proceed to the next set of coordinates.

The morning wore on as the Bell continued ever westward. The going was slow. Though many of the coordinates were but a few miles apart, the Bell’s ceiling constraints forced Hosni to skirt some of the higher peaks, flying through alpine cols and passes that lay below sixteen thousand feet.

Shortly after one in the afternoon, as they were flying northwest to avoid a peak in the Ganesh Himal range, Hosni called, “We have company. Helo at our two o’clock.”

Remi scooted over to Sam’s side, and they peered out the window at the aircraft.

“Who is it?” Remi asked.

Hosni called back, “PLA Air Force. A Z-9.”

“Where’s the Tibetan border?”

“About two miles on the other side of them. No worries, they always send up eyes to watch helicopters out of Kathmandu. They are simply flexing their muscles.”

“Anywhere else and that would be called an invasion,” Sam observed.

“Welcome to Nepal.”

After a few minutes of paralleling the Bell, the Chinese helicopter peeled away and headed north toward the border. They soon lost sight of it in the clouds.

Twice in the afternoon they asked Hosni to land near a rock formation that looked promising, but neither panned out. As four o’clock approached, Sam put a red grease pencil X through the last point on the day’s map, and Hosni headed for Kathmandu.

The morning of the second day began with a forty-minute flight to the Budhi Gandaki Valley northwest of Kathmandu. Three of Karna’s coordinates for the day lay within the Budhi Gandaki, which followed the western edge of the Annapurna range. Sam and Remi were treated to three hours of beautiful scenery-thick pine forests, lush meadows exploding with wildflowers, jagged ridgelines, churning rivers, and tumbling waterfalls-but little else, aside from a formation that, from above, looked mushroom-like enough to warrant a landing but turned out to be merely a top-heavy boulder.

At noon they landed near a trekker’s stop in a village called Bagarchap, and Hosni entertained the local children with tours of the Bell while Sam and Remi ate sack lunches.

Soon they were airborne again and heading north through the Bintang Glacier and toward Mount Manaslu.

“Eighty-one hundred meters high,” Hosni called, pointing to the mountain.

Sam translated for Remi: “About twenty-four thousand feet.”

“And five thousand less than Everest,” Hosni added.

“It’s one thing to see these in pictures or from the ground,” Remi said. “But, from up here, I can see why they call this place the rooftop of the world.”

After lingering so Remi could take some pictures, Hosni turned the Bell west and descended into another glacier-the Pung Gyen, Hosni called it-which they followed for eight miles before turning north again.

“Our friends are back,” Hosni said over the headset. “Right side.”

Sam and Remi looked. The Chinese Z-9 was indeed back, again paralleling their course; this time, however, the helicopter had closed the gap to only a few hundred yards.

Sam and Remi could see silhouettes staring back at them through the cabin windows.

The Z-9 shadowed them for a few more miles, then veered off and disappeared into a cloud bank.

“Next search area coming up in three minutes,” Hosni called.

Sam and Remi got situated near the windows.

As had become routine, Hosni lifted the Bell’s nose over a ridgeline, then banked sharply into the target valley, bleeding off altitude as he went. He slowed the Bell to a hover.

Sam was the first to notice the valley’s surreal landscape below. While the upper slopes were thick with pine trees, the lower reaches looked as if they had been carved by a rectangular cookie cutter, leaving behind sheer cliffs plummeting into a lake. Jutting from the opposite slope and encircling one end was an ice-covered plateau. A runnel of churning water sliced through the shelf and cascaded to the waters below.

“Hosni, how deep do you think this is?” Sam asked. “The valley, I mean.”

“From the ridgeline to the lake, perhaps eight hundred feet.”

“The cliffs are half that at least,” said Sam.

Honsi eased the Bell forward, following the slope, as Sam and Remi scanned the terrain through their binoculars. As they drew even with the plateau, and Hosni came about, they saw that the plateau was deceptively deep, narrowing for a few hundred yards before ending at a towering wall of ice bracketed by vertical cliffs.

“That’s a glacier,” Sam said. “Hosni, I didn’t see this plateau on any maps. Does it look familiar?”

“No, you are right. This is relatively new. You see the color of the lake, the greenish gray?”

“Yes,” said Remi.

“You see that after glacial retreat. This section of the valley is less than two years old, I would estimate.”

“Climate change?”

“Most definitely. The glacier we passed earlier-the Pung Gyen-lost forty feet last year alone.”

Pressed up against her window, Remi suddenly lowered her binoculars. “Sam, look at this!”

He slid over to her side and peered out the window. Directly below them was what looked like a wooden hut half buried in a waist-high ice shelf.

“What in the world is that?” Sam asked. “Hosni?”

“I have no idea.”

“How close to the coordinates are we?”

“Not quite a kilometer.”

Remi said, “Sam, that’s a gondola.”

“Pardon?”

“A wicker gondola-for a hot-air balloon.”

“Are you sure?”

“Hosni, set us down!”

NORTHERN NEPAL

Hosni crabbed the Bell sideways over the plateau until he found a spot he decided was solid enough to bear the helicopter’s weight, then touched down. Once the rotors had spooled down, Sam and Remi climbed out and donned their jackets, caps, and gloves.

Hosni called, “Step carefully! There will be many crevasses in an area like this.”