They secured the end of the rope to one of the poles wedged like an anchor in the opening of the tunnel that led to the crystal cavern, and Craig abseiled down the rope to the water at the bottom of the shaft once more. Gingerly he committed his weight to the rickety remains of the ladder work as he neared the surface of the water and then lowered himself into the water.
Craig made one dive. It was enough to confirm their worst fears. The tunnel leading into the grand gallery was blocked by a heavy fall of rock. He could not even penetrate as far as the remains of the wall built by the witch-doctors. It was sealed off with loose rock that had fallen from the roof, and it was dangerously unstable. His groping hands brought down another avalanche of rumbling rolling rock all around him.
He backed out of the tunnel, and fled thankfully back to the surface. He clung to the timber ladder work panting wildly from the terror of almost being pinned in the tunnel.
Tupho, are you all right?"
"Okay!" Craig yelled back up the shaft.
"But you were right. The tunnel has been dynamited. There is no way out.
When he climbed back to the platform, they were waiting for him. Their expressions were grim and taut in the firelight.
"What are we going to do?" Sally Anne asked.
"The first thing to do is to explore the cavern minutely." Craig was still gasping from the swim and the climb. "Every corner and nook, every opening and branch of every tunnel. We will work in pairs. Sam and Sarah, start working from the left use the lamps with care, save the batteries." Three hours later by Craig's Rolex, they met back at the fire. The lanterns were giving out only a feeble yellow glow by now, the batteries drained and on the point of failing.
"We found one tunnel at the back of the altar," Craig reported. "It looked good for quite a way, but then it pinched out completely. And you? Anything?" Craig was cleaning a scrape on Sally-Anne's knee where she had fallen on the treacherous footing. "Nothing," Tungata admitted. Craig bound the knee with a strip torn from the tail of Sally-Anne's shirt. "We found a couple of likely leads, but they all petered out."
"What do we do now?"
"We will eat a little and then rest.
We have got to try and sleep. We will need to keep our strength up." Craig realized it was an evasion even as he said it, but surprise ingly, he did sleep.
When he awoke, Sally-Anne was cuddled against his chest, and she coughed in her sleep. It was a rough phlegmy sound. The cold and damp was affecting them all, but the sleep had refreshed Craig and given him strength.
Although his own throat and chest were still painful from the gas, they seemed to have eased a little and he felt more cheerful. He lay back against the rock wall, careful not to disturb Sally'Arme. Tungata was snoring across the fire, but then he grunted and rolled over and was silent.
The only sound in the cavern now was the drip of water from the seepages in the roof, and then, very faintly, another sound, a whispering, so low that it might have been merely the echoes of silence in his own ears. Craig lay and concentrated his hearing. The sound annoyed him, niggled at his mind as heried to place it.
"Of course," he recdknized it, "bats!" He remembered hearing it more clearly when he had first reached the platform. He lay and thought about it for a while and then gently eased Sally-Anne's head off his shoulder. She made a soft gurgling in her throat, rolled over and subsided again.
Craig took one of the lanterns, and went back into the tunnel that led to the platform and the shaft. He flashed the lantern only once or twice, conserving what was left in the batteries, and in darkness he stood on the platform with his back against the rock wall and listened with all his being.
There were long periods of silence, broken only by the musical pinging of water drips on rock, and then suddenly a soft chorus of squeaks that echoed down the chimney of the shaft, then silence again.
Craig flicked on the lantern, and the time was five o'clock. He was not certain if it was morning or evening, but if the bats were roosting up there, then it must still be daylight in the outside world.
He squatted down and waited an hour, at intervals checking the slow passage of time, and then there was a new outburst of faroff bat sounds, no longer the occasional sleepy squeaks, but an excited chorus, many thousands of the tiny rodents coming awake for the nocturnal hunt.
The chorus dwindled swiftly into silence, and Craig checked his watch again. Six-thirty, five He could imagine somewhere up above the airborne horde pouring out of the mouth of a cave into the darkening evening sky, like smoke from a chimney pot.
He moved carefully to the edge of the platform, steadied himself on the side wall and leaned out over the drop very cautiously, keeping a handhold. He twisted his head to look up the shaft, holding the lantern out to the full stretch of his arm. The feeble yellow light seemed only to emphasize the blackness above him.
The shaft was semicircular in plan, about ten feet across to the far wall. He gave up on trying to penetrate the upper darkness and concentrated on studying the rock of the shaft wall opposite him, prodigally using up the battery of the lamp" It was smooth as glass, honed by the water that had bored it open. No hold or niche, nothing, except- He strained out over the drop for an extra inch. There was a darker mark on the rock just at the very edge of his vision, directly opposite him, and well above the level of his head.
Was it a stratum of colour, or was it a crack? He could not be sure, and the light was fading. It could even be a trick of shadow and light.
"Pupho," Tungata's voice spoke behind him and he pulled back. "What is it?"
"I think this is the only way open to the surface." Craig switched off the lantern to save it.
"Up that chimney?" Tungata's voice was incredulous in the darkness. "Nobody could get up there."
"The bats they are roosting up there somewhere."
"Bats have wings," Tungata reminded him, and then after a while, "How high up there?" don't know, but I think there may be a crack or a ledge on the other side. Shine the other lamp, its battery is stronger." They both leaned out and stared across.
"What do you think?"
"There is something there, I think."
"If I could get across to it!" Craig switched off again.
"How?"
"I don't know, let me think." They sat with their backs against the wall, their shoulders just touching.
After a while Tungata murmured, "Craig, if we ever get out of here the diamonds. You will be entitled to a share "Do shut up, Sam. I'm thinking." Then, after many minutes, "Sam, the poles, the longest pole in the ladder do you think it would reach across to the other side?" They built a second fire on the ledge, and it lit the shaft with an uncertain wavering light. Once again Craig went down the rope, onto the remains of the timber ladder, and this time he examined each pole in the structure. Most of them had been axed to shorter lengths, probably to make it easier to carry them down through the tunnels and passages from the surface, but the side frames were in longer pieces. The longest of these was not much thicker than Craig's wrist, but the bark was the peculiar pale colour that gave it the African name of "the elephant tusk tree'.