She ran across the cave and flung herself on the surprised Bill. Jack and Dinah followed, shouting in delight. Lucy-Ann caught sight of Philip and flung herself on him too.

"Philip! Dear Philip, you did escape and get to Bill!"

Philip was astonished to see the children and the old couple there. He had left them in the treasure caves. How had they got out? And where were the men?

The old couple came slowly up, half frightened to see so many people by the light of the powerful torches. Bill was gentle with them.

"Poor, frightened moles," he said to Philip. "Well, they will be well looked after and rewarded. Now - where are these men?"

"I bolted them in," said Jack proudly. "They are prisoners in the treasure caves."

This was news to Philip - and, of course, to Bill too. They questioned Jack eagerly, and he told them how the old woman had shown them the hole behind the picture, and how they had managed to escape through it to the cave of echoes and from there to their own fern-cave. Then how Jack had gone to the men's hut, and had come up against Pepi and tied him up - and finally how he had got his Great Idea, and slipped back to bolt the men in.

"Well - that seems pretty good work to me!" said Bill. "But it won't be an easy job routing them out of those caves. I wonder if we could take them by surprise from the back - get in at that picture-hole and give them a shock."

"Oh yes!" said Jack. "Of course you could. You could leave one or two of your men at the bolted door here, attracting the attention of the seven men - and whilst they are shouting and yelling at one another, the rest of your men could go in the other way and surprise them."

"That seems a very sound plan," said Bill, and gave some orders. He turned to Philip. "I'm leaving two men here. Take them to the bolted door in half an hour's time, and they will then attract the men's attention. Jack, you come with me and the others, and show me the way back to your fern-cave, and through the cave of echoes to the pa.s.sage that leads to the hole at the back of that picture."

The little procession set off. The two men left behind waited for half an hour and went with Philip to the bolted door at the bottom of the curving steps. They rapped on it and shouted.

An answering shout came from inside. "Who are you? Let us out! Open the door!"

The men inside banged at the door and the men outside did the same. It was a perfect babel of noise. All the seven men were there, arguing, banging, demanding to be set free, and generally losing their tempers.

Meantime Bill, Jack and the others had gone to the fern-cave. They had crawled in, and found to their dismay that they had to wriggle through the drain-pipe hole at the back. One of them almost got stuck.

"I must say you children manage to get into the most marvellous sc.r.a.pes," said Bill, emerging from the hole into the cave of echoes. "My, I'm hot!"

"Hot, hot, HOT, HOT!" said the echoes at once. Bill jumped. "What's that?"

"That, that, THAT, THAT!" shouted the echoes alarmingly. Jack laughed. "It's only the echoes," he said. Kiki began to squawk, and then whistled like an express engine. The noise was deafening.

"Kiki always does that here," said Jack, leading the way. "Shut up, Kiki! Bad bird!"

Soon they were in the pa.s.sage that led to behind the waterfall - but before they got there they came to the hole in the roof.

"Have you got a rope on you, Bill?" said Jack. "We've got to get up here. I used my rope to tie up Pepi. If you can get me on your shoulder, and shove me up, I can crawl into the hole, fix the rope and let it down."

It was soon done. One after another the men crawled into the hole, thinking that never in their lives had they done so much climbing, creeping and crawling. They looked at Jack in admiration. What a boy!

Jack came to the hole behind the picture. He listened. Not a sound. The men were all at the bolted door, shouting, kicking and arguing.

Jack gave the picture a push and it fell. The room was empty. He jumped down and the others followed one by one.

"Hope there's no more of this, sir," said one of the men to Bill. "You want thinner men for this job."

"Better go cautiously now," said Jack. "We are near the treasure caves. We go straight through three and then come to the cave of statues. That's where the bolted door is."

"Quiet now," ordered Bill, and, treading softly in their rubber-soled shoes, the men moved slowly forward, revolvers glinting in their hands.

Through the cave of gold - through the cave of books - through the cave of pictures. Jack laid his hand warningly on Bill's arm. He could hear something.

"It's the men," he said. "Hark! - they must have got rocks or something to hammer at the door like that. That really will break it down, I should think, by the noise.

Bill stepped from the tunnel into the cave of statues. Although he had been prepared for them by Philip, he could not help jumping a little when he saw them in that dim greenish glow. His men stepped silently behind him.

At the far end were the seven men. They had found a big rock and were using it as a battering-ram. Crash! It struck the door violently. Crash!

"Now's our chance," whispered Bill. "They have their hands full - not a revolver to be seen among them. Come on!"

The men moved swiftly up behind Juan and the others. A sharp, stern voice barked out behind them: "Hands up! We've got you cold!"

The men all had their backs to Bill. At his voice, they jumped in surprise, and put their hands above their heads at once. Then Juan swung round, his hands still high. His eyes swept the stern group of men in front of him.

"How did you get here?" he said, between his teeth. "What other way in is there? Who locked us in?"

"No questions answered now," snapped Bill. He called loudly to the two men outside the door.

"Hey, Jim! Pete! Unbolt the door. We've got 'em."

The door was unbolted. It swung open and Jim and Pete looked round it, grinning. "Pretty little play we had," said Pete. "Quite enjoyed it, I did."

Jack slipped down too. The girls had been told to keep away till the men had been captured. They were with the old couple in the cave of stars, waiting impatiently.

Bill counted the men. "All seven here. Good. And we've got the eighth all right too. Pete, take these fellows back to the planes. Shoot at the first sign of any trouble. I'll stay here and have a look-see. It looks mighty interesting."

The men were marched off, handcuffed, swearing and stumbling. Jack watched them go, delighted to think that he had had the idea of bolting them in. Bill had clapped him on the back for that.

Once the men had pa.s.sed through the cave of stars, the girls came running to join Jack, Philip and Bill. They showed the astonished Bill everything. He whistled when he saw so many treasures.

"Fortunes here," he said. "Well, it won't be an easy task finding out where all these things came from and sending them back. Perhaps Julius Muller can help."

"And the old couple can too," said Lucy-Ann eagerly. "They know the histories of most of the statues, anyway."

The old man and his wife were collected on the way out and taken with everyone else to the planes. They made no objection now to going into the open air. They evidently thought that Bill was some Great Man Who Must Be Obeyed. They bowed to him whenever he spoke to them.

"We'll have to take them with us for questioning," said Bill. "But we'll return them as soon as possible - to the village where this good man, Julius, lives. He may be good enough to look after these old people."

Everyone got into one or other of the planes. There were six of them. In three of them were the eight prisoners with their guards. In two others were pilots and the old couple. Bill's plane carried the children.

Their plane rose up, and the children looked down at the strange valley for the last time.

"Yes, have a good look," said Bill. "It will be in all the papers presently - the Valley of Treasure."

"No, Bill - the Valley of Adventure!" said Jack. "That's what we shall always call it - the Valley of Adventure!"

"I'm glad we found Martha all right," said Lucy-Ann suddenly. "I did like her so much. She was sweet."

"Good heavens! Who's Martha?" said Bill, startled. "I thought the old woman was called Elsa. Don't tell me Martha is someone we've left behind!"

"Oh no, Bill - she's sitting on Elsa's knee now in one of the other planes - she might even lay an egg there," said Lucy-Ann.

Bill looked even more astonished. "She's a hen!" explained Lucy-Ann. "She got left behind in the caves with the men and we were afraid she might have been killed by them. But she wasn't. She hid under the table and came clucking to join us when we went to find her. You were busy looking at the gold, I expect."

"I must have missed her," said Bill. "To think I haven't yet made the acquaintance of one of the ladies in this thrilling adventure. What a pity!"

"What a pity, what a pity, what a pity!" said Kiki at once. "Cluck-luck-luck! Pop goes Martha!"

THE END.