They were all breathing heavily, gulping water, sweating.

“What a view,” said Anya, leaning over the edge.

A sheer cliff dropped away at her toes. Behind them climbed a steep-walled granite dome. Across the plateau, the stubbed ends of timbered pillars stuck up out of the ground. More sprouted across the curve of the dome.

Squinting his eyes, Tucker could almost make out the bases of old fortifications and the foundations of long-lost buildings.

“This is the Klipkoppie,” Christopher announced.

“Not much left of it,” he said.

“No. Time and erosion have done their job. A hundred twenty years ago, this was a massive fort. The watchtower sat atop the dome. From here, Boer soldiers could see the entire valley below. The only access was up that narrow ravine we climbed.”

“A natural choke point.”

“Exactly so.”

Tucker began to wander into the ruins, but a shout from Christopher halted him.

“Step carefully! This plateau is riddled with tunnels and old cellars.”

“Here?” Anya asked. “This looks like solid rock.”

Tucker knelt and probed the earth with his fingers. “Sandstone. Definitely workable. But it would’ve taken hard labor and patience to excavate here.”

Christopher nodded. “Two qualities the Boers were known for. The entrances are covered by old planks—probably very fragile by now. Below us are sleeping quarters and storage areas.”

Tucker called to Kane, who had wandered off to explore. “COME.”

The shepherd galloped over and skidded to a stop.

Kneeling, Tucker opened his canteen and filled his cupped hand. He rubbed the water over Kane’s snout and under his chin. He held his damp palm to his nose. “SEEK. EASY STEP.”

Nose to the ground, Kane padded off, following the edge of the plateau.

“What’s he doing?” asked Anya.

“Setting up a search parameter.”

Kane began working inward, crisscrossing the dirt with his nose to the ground. Occasionally he would stop suddenly and circle left or right before resuming course.

“Tunnel openings,” Tucker explained to Anya and Christopher.

“Remarkable,” Christopher murmured.

Kane suddenly stopped a quarter of the way across the plateau. He circled one spot, sniffing hard, stirring up dust eddies with his breath. Finally, he lay down and shifted around to face Tucker.

“He smells moisture there.”

The trio worked cautiously toward him. Christopher led the way, thumping his walking stick against the ground, testing each step.

Once they reached Kane, Tucker gave his partner a two-handed neck massage. “Atta boy.”

Christopher lifted his walking stick and drove the butt of it hard into the dirt, at the spot where Kane had been so vigorously sniffing.

There came a dull thunk.

“Impressive beast of yours!” Christopher said.

Unfolding the small spades in their packs, the trio dug and swept away the packed dirt until a square of planking was exposed. It looked like a trapdoor into the earth. Luckily, the rough-hewn wood was rotted, desiccated by a century of heat. Jamming their spades into crannies and splits, they slowly pried the planks free and set them aside, exposing a dark shaft, about a yard across.

Lying on his belly, Tucker pointed his flashlight down the throat of the tunnel. Kane crouched next to him, panting, sniffing at the hole.

“Looks to drop about eight feet,” he said, rising to his knees. “Then it branches off to the left.”

“Who goes first?” Anya asked.

As if understanding her, Kane gained his feet and danced around the hole, his tail whipping fast. He looked up at Tucker, then down at the shaft.

“Take a guess,” Tucker said.

“You’re sending him down there?” Anya crossed her arms. “That seems cruel.”

“Cruel? I think Kane was a dachshund in a former life, a breed built to flush badgers out of burrows. If there’s a hole, Kane wants to crawl in and explore.”

Tucker pulled the shepherd’s tactical vest out of his backpack. Anticipating what was to come, Kane shook and trembled with excitement. Tucker quickly suited up his partner, synching the feed into the new sat phone Harper had supplied. He ran through a quick diagnostics check and found everything working as designed.

“Ready, Kane?”

The shepherd walked to the shaft and placed his front paws on the lip. Tucker played the beam of his flashlight across the sides and down to floor of the tunnel. He pointed.

“GO.”

Without hesitation, Kane leaped into the darkness, followed by a soft thump as he landed at the bottom.

“SOUND OFF.”

Kane barked once in reply, indicating he was okay.

Tucker punched buttons on his phone, and Kane’s video feed came online. Shading the screen with his hand to reduce the sun’s glare, he was able to make out the horizontal tunnel that angled away from the shaft. The camera had a night-vision feature, but Tucker tapped a button, and a small LED lamp flared atop the camera stalk, lighting Kane’s way.

The sharper illumination revealed coarse walls, shored up by heavy timber. Out of the sun and wind, the wood looked solid enough, but looks could be deceptive. Back in Afghanistan, he’d witnessed several tunnel collapses while hunting for Taliban soldiers in their warren of caves.

Fearing the same now, he licked his lips, worried for Kane, but they both had a duty here.

Speaking into his radio mike, he said, “FORWARD. SEEK.”

Hearing the command, Kane stalks forward. He leaves the glaring brightness of the day and heads into darkness, led by a pool of light cast over his shoulders. His senses fill with dirt and mold, old wood and stone—but through it all, he fixes on a trail of dampness in the air.

It stands out against the dryness.

He needs no lights to follow it.

But he goes slowly, stepping carefully.

His ears pick out the scrunch of sand underfoot, the scrabble of chitinous legs on rock, the creak of timber.

He pushes through faint webs of dust.

He reaches another tunnel, one that crosses his path.

Which way?

A command whispers in his ear. His partner sees what he sees.

SEEK.

He steps to each direction, stretching his nose, breathing deeply, pulling the trail deep inside him, through his flared nostrils, past his tongue, to where instinct judges all.

He paces into one tunnel, then another, testing each.

Down one path, to the left, the air is heavier with moisture.

His ears hear the faintest tink of water falling to stone.

He heads toward it, his heart hammering inside him, on the hunt, knowing his target is near. The tunnel drops deeper, then levels. Several cautious paces farther and the passage opens into a cavern, tall enough to jump and leap with joy within.

He wants to do that.

But instead he hears, HOLD.

And he does.

He stares across the sloping floor of the cave, to a pool of glassy blackness. The sweep of his light bathes across the surface, igniting it to a clear azure blue.

Water.

“Eureka,” Christopher murmured.

Tucker turned to the others and passed Anya his phone. “I’m going down there. When I reach Kane, I’ll check in, using his camera.”

He turned, fished through his pack, and pulled out his handheld GPS unit. He stuffed it into a cargo pocket of his pants.

“I don’t understand,” Anya said. “Why do you have to go down there? It doesn’t look safe for someone as big as you.”

Tucker scooted to the hole and swung his legs over the edge. “We need accurate coordinates.”

“But why?” Concern shone on her face. “We know the well is below this plateau. Isn’t that close enough?”

“No. We need a compass bearing from that exact spot. Any miscalculation of the well’s location will be compounded exponentially two hundred miles away.” He pointed toward the horizon. “Make a hundred-yard mistake here, we could be off by a mile from De Klerk’s coordinates. And out in the broken and inhospitable terrain of the Groot Karas Mountains, we could spend months up there and never find it.”