"Please go away," Ko groaned.

"Lie flat," Zircon ordered.

There was the sound of ripping cloth. Zircon grunted. "Hmmmm."

Ko moaned. "I wish to go to my ancestors alone."

"You're not going to your ancestors," Zircon replied scornfully. "I doubt that they'd have you. In case you're interested, Rick's bullet merely plowed a nice, round hole through some of the fat on your right side. You haven't even lost enough blood to make the wound interesting."

Ko's voice was suddenly animated. "Are you sure?"

"Quite sure. No, don't try to get up. Stay where you are. If you try to run I'll order our seeing-eye marksman to finish the job." Zircon continued, "Rick, Scotty, Chahda. Stay where you are. I saw some torches stacked in one of the tents. I'll get them and be right back."

The three boys a.s.sured him that they wouldn't move. Rick, for one, had no intention of prowling about in the blackness.

While they waited, Scotty asked, "What happened to you, Rick?"

Rick hesitated. He couldn't give an adequate account of what he had experienced during the recent hours. Or was it weeks? He summed it up.

"After we got separated, I couldn't find you again. I wandered around.

Then I sat down in a big cave and fell asleep. When I woke, there was a Tibetan with a candle. I followed him to a boat landing, slugged him, and rowed across the lake. He's waiting, tied up, across the lake at the spot from where I fired. How about you?"

"We look for you," Chahda said. "We look a long time, and almost get lost ourself."

"Finally we decided we'd better push on and find Long Shadow," Scotty continued. "We tracked the drippings from the candles for hours. It was slow work. Then, while we were resting, we got jumped from behind. They didn't even have to bother about lights, because one of our flashlights was on, and it was getting so weak we couldn't see more than ten feet.

They came out of the darkness with a rush and there we were. They made us walk to the boat landing, called the boats from here, and brought us over. We've been sitting in one of those tents for hours. You know the rest."

How rapidly they could cover the tortured hours of travel in a few words, Rick thought. But he said only, "I'm glad we're all together again."

"How you see in dark?" Chahda asked.

Rick explained briefly. The Hindu boy chuckled. "Plenty mystery for one who not know, you bet! I scared myself, like the men who ran."

Then Zircon came back. He brought out matches and in a moment torches were blazing again. They bandaged the two enemies as best they could, using clean handkerchiefs which Chahda and Scotty carried. And Rick got his first good look at Long Shadow's face.

The man was incredibly thin. His skin was stretched over the bones of his face like parchment, and it had a sallow ivory tinge even in the ruddy torchlight. His eyes were black, with just the faintest hint of a Mongoloid fold.

"Are you a Eurasian?" Rick asked bluntly.

"Yes." Long Shadow smiled. "I'm one quarter Burmese. The other three-quarters doesn't matter."

"You know our names," Rick said. "I'm sure you do. But we don't know yours."

Long Shadow laughed. "You could never p.r.o.nounce my Burmese name and the other name I use is of no importance."

Zircon and the others had been listening. Now the scientist said, "We'll have plenty of chance to talk, Rick. At the moment I'm concerned with getting out of here. After a bit of exploration of course. It's almost certain that the heavy water comes from here. Although I don't know the source."

Scotty motioned toward the Lake of Darkness. "Bradley said to bring a Nansen bottle and a rubber boat. He must have known about this. Why would he say to bring a Nansen bottle if not to take a sample from the lake?"

Zircon flashed a look at Long Shadow. The Eurasian smiled gently.

"That's a good question Mr. Scott asked," he told them. "But don't look to me for the answer."

"Search the tents," Zircon ordered. "Chahda, keep an eye on our two friends."

The three Americans walked to the felt tents and began searching through them. Zircon used the infrared camera. Rick and Scotty took torches.

Rick was feeling through a pile of furs when Zircon called, "Here are the flashlights!"

Zircon's had run down, but Scotty's, and Chahda's big lights were still useful. They made the search much easier. Rick went back to the pile of skins and found that they were plastic-lined water bags, similar to the ones they had found on the way to Korse Lenken. Then, stacked in a corner of the tent, he found some Nansen bottles!

At the same moment, Scotty called from the next tent. "Look what I found!"

He had located the ammunition supply. There was powder and ball for the old muskets the Tibetans used, two boxes of machine pistol cartridges, and a small case of grenades!

"Now we know where Ko got the one he tried to use on us," Rick said.

"But where did they come from in the first place?"

"The war," Scotty guessed. "There must be tons of ammo and ordnance of all kinds floating around China. What makes me wonder is why the Tibetans don't have modern rifles."

"I suspect the answer is their natural conservatism," Zircon suggested.

"They are slow to change. And such guns as they use are handed down from father to son. I don't doubt that modern rifles were offered them and that they refused."

Rick knew something of the Oriental mind, although not much, and he realized that Zircon was probably right. In a land of ancestor worship, change was resisted.

Scotty stuffed grenades in each pocket. "Just in case we get into a fight on the way out," he explained.

Rick was glad to leave the deadly things to his friend. Scotty knew about grenades from his tour of duty in the Marines; he had thrown more than a few himself.

"Nansen bottles in the next tent, professor," Rick said. "There must be something to this business of getting stuff out of the lake. But golly, you don't get heavy water out of natural water, do you?"

"I don't know," Zircon said. "There is only one precedent I can think of. Have you ever heard of Lake Baikal?"

Neither boy had.

"It's a very large lake in Siberia, just above Mongolia," the scientist told them. "It is also very deep. A few years ago, before the Iron Curtain closed down, word came out of Russia that some scientists had succeeded in getting heavy water samples out of Baikal. That is the only precedent that I know.

"It is true," he continued, "that heavy water has a tendency to sink.

Naturally enough, since it is heavier. But for enough to form on the bottom of a body of water, there would have to be great depth and complete calm. Any current would stir the water up and the heavy water would merge with the normal once more."

"In other words, you need a lake like this one," Rick concluded.

"I must admit it fits the requirements," Zircon agreed. "And we've seen no sign of an industrial plant. These caverns certainly would be no place for one."

"We can soon tell," Scotty suggested. "Let's take a sample. When we get out, you can test it."

"Quite right," Zircon said. "And let's be quick about it."

It didn't take long to discover the reason for the odd little derricks on the barge. Each was equipped with a pulley and a reel of wire.

Obviously, it was from here that the Nansen bottles were lowered.