He stumbled over something on the ground. “Let me have the lighter.”

She palmed it to him. He flicked it on and saw rail tracks laid onto the floor of the tunnel. An old handcar, or pump trolley, sat on a nearby siding.

A volley of shots sent them diving to the ground. Flashlight beams lanced up and around them.

“Get on the handcar,” Gideon whispered. “Quickly.”

In a second Alida had leapt onto the cart. Gideon gave it a shove, running it onto the main track and up to speed, then jumped on himself. The pump handle moved up and down with a creaking of metal, rusty and covered with dust but still in working order. Gideon worked the handle to keep it going as more rounds ricocheted through the cavern. The car went squealing along the metal track, gaining speed as it entered a downhill grade.

“Oh, shit,” said Alida.

Gideon stopped pumping—but it made no difference. Faster and faster went the pump, its twin handles flying up and down on their own. The shots and cries began to recede.

“This was a really bad idea,” said Alida, crouching and gripping the wooden sides of the handcar.

The car was now barreling downhill, in utter blackness, heading for only God knew where.

They careened along the track, unable to see anything. A stale cave-wind whistled past Gideon’s head as he crouched in terror, groping for a better handhold, bracing for the inevitable crash.

“A brake!” yelled Alida. “This thing’s got to have a brake!”

“Why didn’t I think of that?”

He flicked on the lighter, and—in the brief spark before it went out—made out an old iron foot pedal on the side of the car, between the sets of wheels. Desperately, he jammed down on it with his foot. There was an earsplitting screech, an explosion of sparks burst around and behind them, and they were thrown forward as the cart decelerated, vibrating wildly, threatening to jump the tracks. He quickly eased up and applied the brake more evenly, slowly increasing the pressure. The cart wailed and groaned and finally came to a shuddering halt.

“Nice work, Casey Jones.”

Gingerly Gideon got off, then flicked the lighter. The tunnel stretched on ahead, making what looked like the beginning of a long curve. Not far ahead, however, a large pile of rocks lay across the tracks, apparently having fallen from the ceiling. The tunnel was blocked across its entire width.

“Jesus,” muttered Alida. “You stopped us just in time.”

Gideon could still make out, far away, the distorted, echoing voices of the NEST team. They had only gained a few minutes.

“Come on,” he said, taking her hand.

He jogged forward to the rock pile and they began to climb it, Gideon flicking on the lighter every few seconds in order to orient themselves. He could hear the sound of distant running.

“I don’t need hand-holding,” said Alida, trying to shake free of his hand.

“I do.”

At last they reached the top of the pile and clambered down the other side. They made their way on down the tunnel as quickly as they could, climbing over two additional cave-ins, until at last they reached one that blocked the tunnel completely.

“Damn,” said Alida, staring up at the rock pile. “Did we pass any side tunnels back there?”

“None,” said Gideon, staring at the pile of loose rocks. He held the lighter up. The ceiling was rotten, but there was no opening or way through. It was a dead end.

“We’d better figure out something quick.”

“Like I said, we didn’t pass any side tunnels. But we did pass some blasting supplies.”

“No. Oh no.”

“You stay here.”

Gideon picked his way back. The voices were getting louder, and he thought he could see the faint flicker of light in the dusty air. Their pursuers were coming on fast.

He reached the supplies—stacks of blasting mats, boxes of wadding, old drill bits, cord. There was a cache of wooden boxes in a far corner, and he ripped the rotten lid off one: blasting caps. He tried to lift the box but it collapsed, the caps spilling all over. Everything was rotten.

Now flashlight beams were flicking about, piercing the rising columns of dust. “Hey! Over there!” came a shout, followed by a shot.

Gideon extinguished the lighter, dropping into a crouch. If a bullet hit these blasting caps…

Another shot, the light beams playing about, looking for him. They were too close; there was no time to jury-rig a bomb. Only one thing to do. Crouching, he ran back down the dark tunnel for a few hundred feet, then turned and knelt. Aiming the live handgun with one hand, he flicked the lighter with the other. It cast just enough illumination for him to take aim at the heap of blasting caps. Beyond, a crowd of flashlight beams danced in the murk.

“There!” came a voice.

A volley of shots rang out as he squeezed off his own shot. There was a violent explosion, then a roar that punched him backward, knocking the wind from him, followed by a shuddering crash as the ceiling collapsed.

Shaking his head to bring himself back to his senses, Gideon scrambled to his knees in the blackness and crawled back the way he had come. The ground continued to shake with secondary collapses, rocks and pebbles falling all around him. He finally managed to get to his feet and, with a few more flicks of the lighter, make it back to the spot where Alida was waiting. She was crouching, coated with dust, and furious.

“What the hell did you do?”

“They were too close. I had to shoot at the blasting caps, blow the tunnel up.”

“Christ almighty. And that huge noise afterward? Was that a cave-in?”

“Right. The ceiling collapsed, blocking the tunnel. Now we’re safe—at least for the moment.”

“Safe? Are you nuts? Now we’re trapped!”

They began retracing their steps toward the fresh cave-in, looking for side tunnels or shafts they may have missed. There was nothing. Gideon was exhausted: his ears rang, his head pounded, and his mouth was full of muddy paste. They were both coated with dust and could hardly breathe in the choking air. Arriving at the cave-in, Gideon inspected it with the flame of the lighter. It was a massive heap of rocks, wall-to-wall, impassable. Gideon peered up at the irregular hole in the ceiling from which the rocks had fallen.

He snapped the lighter off and they were once again plunged into darkness. He could hear muffled voices from the far side.

“What now?” Alida asked.

They sat in silence for a while. Gideon finally removed the lighter, flicked it on, held it out.

“What are you doing?”

“Looking for movement of air. You know, like they do in novels.”

But the flame burned utterly straight. The dust was so thick he could barely see. He flicked it off again. “It’s possible,” he said, “this cave-in opened a hole in the ceiling up there. I’m going up to check.”

“Be careful. It’s unstable.”

Gideon climbed the pile of rock. Each footfall sent more rocks and pebbles sliding down, including some larger ones that detached from the ceiling and crashed onto the pile. The rocks led all the way up to the concave hole in the ceiling. He scrambled to the top, sliding back a little with each step, the dust choking him, invisible rocks raining down all around—and suddenly, at the very top, he found air that was fresh and clear. He looked up and saw a star.

They crawled out into the dark and lay in a patch of sweet-smelling grass at the bottom of a ravine, coughing and spitting. A small stream ran down the ravine, and after a moment Gideon got up, crawled to the stream on his hands and knees, washed his face, and rinsed his mouth. Alida did the same. They appeared to be below the Los Alamos plateau, in the warren of heavily forested tributary canyons cutting down to the Rio Grande. Gideon lay back on the ground, breathing hard and looking up at the stars. It was incredible they had escaped.