It was strange to be kneeling, working with groping hands, watching the faces of Chepe-Noyan, the guards, and Van Groot, while his fingers worked frantically.

He took the cut film from the holder and plunged it into the developer. Then he began agitating it.

He was the center of all eyes - fearful eyes.

His friends were afraid the trick would not work.

Van Groot was afraid it would.

The Mongols were afraid, because here was magic they did not understand.

Subotai toyed with his knife, and his eyes on Rick were black and cold, with that strange, animal glint in them.

Sweat stood out on Rick's face and trickled down his nose.

He took the film from the developer and put it into the fixative, almost dropping it. To the watchers he seemed to be kneeling motionless. They couldn't see his hands.

The film would be a negative, of course. But maybe that was good. Chepe-Noyan would see himself as a white image in a frame of mottled grays and blacks, for the Mongol was darker in color than the white stone around him, and the negative was reversed ... Rick's train of thought broke off. He took the film from the stopper and swished it in the water. It wasn't a good job of developing, but it would serve.

"Now!" he shouted, and pulled his arms free and thrust the velvet tent aside.

He ran to the throne and held the negative up before the Mongol's eyes, so that he might see through it and see that his soul had been captured.

The Mongol shrugged.

Van Groot hid a smile.

Rick turned white.

The film was a solid, formless gray!

Chepe-Noyan's face darkened with anger. He made a disdainful gesture and spoke to Van Groot. The man answered briefly.

Rick turned to his friends. "It's fogged! I ... but it can't be! The camera is new, and the film was all right."

Suddenly Zircon let out a great roar. "I have it! I know why it was fogged. Radioactivity! I knew there was something familiar about the rock where we camped that last night. It was pitchblende! Radium and uranium ore! Rick, radioactivity fogged your film. Lord, it must be enormously high-content ore!"

He leveled a finger at Van Groot. "That is why you wanted to keep us away. You had discovered a big deposit of pitchblende. You needed time to make arrangements to develop it. Isn't that what you were doing in Bombay?"

Van Groot's smile was gone now. "Yes," he said. "I was working out the details, trying to get mineral rights from the Tibetan government, trying to get backing. I would have succeeded, tool I will succeed! Knowing about it will do you no good, my friends!"

And then Chepe-Noyan spoke. Rick saw Weiss's brows lift slowly. It was evident that the ruler's words amazed him.

"We are not to be executed," he translated.

As one, the party relaxed. But what was to be their fate?

Rick could see that Van Groot was as much interested as they were. And as Chepe-Noyan informed them of their fate, he could see that it did not meet with the dapper man's approval.

"We are to be placed on the Hill of the Thousand Repentant Ancestors," Weiss went on, following the ruler's words. "It is the high plateau beyond this building. The reason for this punishment is that, as white men, we may have souls of a different sort."

He quoted the Mongol word for word now. "'No food, no water will be given the prisoners. If they are immortal, they can eat stone. If not, they will starve and die, and their blood will not stain the Valley of the Golden Tomb!'"

When he had finished this p.r.o.nouncement, Chepe-Noyan rose without another word and parted thru draperies behind his throne, signifying that the audience was ended. But Van Groot moved quickly to his side, and Rick could see that he was pleading with the ruler about something.

Rick looked at his friends. It was a relief to know they were not to be killed outright. But was their punishment on the plateau to be any more pleasant than immediate death?

He remembered the barrenness of the plateau he had seen. It towered above the city and on its height a man would be at the mercy of the cutting winds and the rains that swept across these Tibetan peaks. And without food...

Suddenly there was a command from the throne. Chepe-Noyan had pushed Van Groot aside and was parting the draperies again. He pointed to the prisoners and spoke a word in Mongol. The guards advanced toward them and with a wave of their flat swords, signified that the prisoners were to start marching!

Rick saw Van Groot's face as he turned to go, and it was white with rage. He turned his head to follow the line of the man's eyes. The rest of the guards were picking up the electronic equipment and carrying it after the party.

They were to be placed on the plateau with all their belongings!

Van Groot's fists clenched and in two bounds he was beside the guards who were removing the equipment. He forced a smile and reached for one of the boxes.

Rick understood his action when he recognized the box as the one that contained the storage batteries.

The guards paid no attention to Van Groot's movements. And as Rick was pushed out of the throne room, he saw the man carrying the batteries out another entrance.

He gave the matter no further thought for the moment. The guards' prodding swords made anything but moving an impossibility. The prisoners soon found themselves in a courtyard.

Every eye in the party went to the high plateau and traveled up.

The plateau was two hundred feet high, sheer on all sides and with a flat, oblong top about a hundred feet long and fifty feet wide. Rick wondered how they would get up there with all the equipment. But there was no more chance to survey their prison - the swords prodded again and they were marched across the wide grounds.

As they approached the rocky wall of the hill, he saw what appeared to be a tunnel opening in the base. It was blocked by a square stone.

The guards halted them, and two men began to push aside the square rock. Behind the prisoners, other warriors arrived with the equipment.

The rock moved slowly and the opening loomed dark. The air was musty, as though it had been closed for centuries. As the guards motioned them inside, Rick wondered how the place had gotten its name.

A few yards inside, stone steps wound upward through the solid rock. Such a mammoth job of carving would have amazed Rick under other circ.u.mstances, but he gave it no thought as they began the long climb.

The Mongols were tireless, and though Weiss was soon breathing hard, they ignored Zircon's plea to let the little professor rest, and prodded the party on. They climbed endlessly through darkness relieved only by a torch in the hands of Subotai, who led the way.

Rick and Scotty waited until the procession had strung out a bit and then moved to Weiss's side and took his arms to help him up the stairs. It seemed as if a whole day had pa.s.sed, when they finally came to an opening directly above their heads and saw blue sky.

One of the guards had moved levers that lifted a circle of stone from an entrance leading out directly to the flat top of the plateau. He growled at them and they scrambled through the opening.

Julius Weiss collapsed in a heap at the feet of the warrior, and the others lifted him and dragged him to one side. The guards lifted the electronic equipment through the hole in the plateau top and piled it around the prisoners.

Subotai then ordered his men down the stairs again. They saw his cruel face disappear and saw the lid swing shut. It dropped with a thump into the hole, and Rick saw that it was flush with the surface of the plateau. It would be impossible to pry the lid up.

They hurried to the rim of their prison and looked straight down. A crowd of Mongols had gathered about the base and were looking up, chattering excitedly.

Around them, the high Tibetan mountains rose, crouching like glacial sentinels.

There was no way off the Hill of the Thousand Repentant Ancestors - except through death.

CHAPTER XVIII.

The Long Night

THERE was no use discussing means of escape, Rick knew. There were none. Their entire prison could be taken in at a glance. It was one flat expanse of rock, broken only by the thin circle that marked the trap door.

Julius Weiss was sitting up now, but he was still breathing heavily.

Rick wandered among the piles of equipment, looking at the labels on each crate.

"I wonder why they brought all this stuff up here with us?" Scotty asked.

"Easiest way to get rid of it, I suppose," Rick answered. "Then they might have been superst.i.tious about it, too." He looked at the equipment idly. "Everything but the batteries," he said. "And you know why Van Groot copped onto those!"

"Afraid we'd send a message?" Scotty guessed.

"Sure. He thought they were our main supply." Rick snapped his fingers. "But who says we can't still try to send a message? He didn't know about the steam generator."

Zircon looked up. "Without a power supply? We have no water for the steam engine. And without the batteries, we have no filament voltage."

Rick started searching through the equipment. "We still have that little twelve-volt charging unit, haven't we?" he asked.

Zircon rose and pointed it out to him. "There it is. But what can we use to turn it?"

"If we could turn it, would we get twelve volts from her?" Rick asked, reaching for the crate containing the little generator.

"But how can we turn it?"

"Windmill."

The scientist seemed interested for a moment and then shook his head skeptically. "We have the crates so we could make one, I suppose. But what good would it do? The big transmitter takes such a heavy load, twelve volts would do little more than tickle it. I doubt that we could even get the tubes heated properly with so little voltage."

"Well, you know best," Rick said gloomily. "But just sitting here seems like giving up pretty easily."

Weiss rose on his elbows. "Why not try it, Hobart?" he urged. "Who can tell?"

Zircon shrugged his shoulders. "No harm in trying," he agreed. "Let's give it a chance, anyway."

Weiss rose to his feet to help Zircon uncrate the generator, while Rick and Scotty started tearing boxes apart to build a rude windmill.

"Save every nail, well need them," Rick said.

Scotty nodded and started making a small pile of the nails beside him. They found a spool and tore the wire from it, deciding to use it as a pulley. A long bolt was chosen as an axle, and the boys decided to use belts for the power drive. Rick's belt was back on the mountain, but Zircon's, added to Scotty's, gave length enough.

Slowly the windmill took shape, and they turned the wooden box staves, serving as blades, into the wind, twisting the blades to give them the proper pitch.

Rick scratched his head when they came to the problem of gearing, but Zircon dropped his work of erecting the radar equipment and came to their a.s.sistance. He did some rapid figuring on the gear ratios and picked out the spools in the equipment for them to use.

They stripped the wire from the spools, installed them in the rickety windmill, and then prepared to install the belts.

"Boy, you can't beat a college education, can you?" Scotty joked, as they looked at their masterpiece.

Rick grinned back at him and then looked to see what progress the two scientists were making.

"Well, that's it," Zircon announced finally. He looked out across the mountains as though wondering if such feeble equipment could push a message by them.

"Shall we try it?" Weiss asked nervously.

The boys slid the belts into the pulleys and held their breath. Slowly the blades began to revolve, then faster and faster.

"It's turning the generator," Rick said excitedly.

Zircon bent over the radar modulator and shook his head. "Just as I said," he informed them. "The power's so weak it hardly lights up the tubes."

The others bent to look at the tubes. They were barely glowing.

"And we have no power for our receiver," Weiss added. "Not that it matters. We wouldn't receive anything, anyway."

"Bigger miracles have happened," Scotty said. "They might hear our message and answer."

"That isn't what he means," Rick explained. "Any radar set that picked us up wouldn't be equipped to send messages. That isn't how ordinary radar works. Only the equipment on Spindrift Island and ours here are rigged up to send messages."

"That's right," Scotty remembered. "Regular radar isn't like dots and dashes, is it?"

Rick shook his head. "Well," he said to the scientists, "shall we give it a try?"

Zircon squatted at the key and took a deep breath. Then his fingers began to tap. Weiss's eyes flew anxiously from piece to piece of the strange-looking rig spread out on the plateau.

It was a tiny hope, this attempt to reach the outside world. Blind transmission. If the signal were picked up, Rick mused, no one would be able to tell them it had been heard. That wouldn't matter, of course, if they could send help; but the hope was small.

Zircon was rapping away expertly on the key and Rick's ear picked up the message. He was sending their approximate lat.i.tude and longitude and describing their plight.

When Zircon finally tired, he turned the key over to Weiss. The little scientist repeated the message over and over, meanwhile scanning the horizon with his eyes.

The swift Tibetan sun was touching the edge of the peaks now, and night would soon be on them. Rick looked up at the windmill and saw that it was still turning merrily.

"We can send from now till kingdom come, if the wind keeps up," he remarked to Scotty. "Maybe we can send all night."

"I wish I could help," Scotty commented, with a wistful look at the radar key.