“Yes, they do,” Reston admitted, “but wouldn’t Ben and Waldo have suspected something odd when they found all the diamonds hidden in one place?”

Jupiter nodded eagerly. “Yes, but I don’t think Old Ben found them that way! We are right on top of the San Andreas Fault here, as you know. The cave is filled with the debris of large earthquakes that occurred some years ago. We haven’t had a large quake for many years, but small ones are always happening.”

“You mean you think there was an earthquake here just recently?” Pete asked.

“Yes, I do. I think that a small earthquake about a month ago disturbed the hiding place of the diamonds. Old Ben and Waldo, digging as usual, found the diamonds scattered in the dirt and thought that they had found a mine!”

“Wow!” Pete exclaimed.

Reston nodded. “Yes, it’s quite possible. However, boys, you must remember that a detective has to consider all possible explanations, and there is another possibility. Old Ben or Waldo may have stolen the diamonds themselves, and are now only recovering them after the earthquake buried them.”

Jupiter reddened. “Of course, I should have considered that.”

“But, Mr. Reston,” Bob said, “Old Ben and Waldo have been here a long time! They’re local characters. They couldn’t have come from Europe only five years ago.”

Reston smiled. “Remember, Bob, that I said Laslo Schmidt is a master of disguise and impersonation! He could be impersonating one of them.”

“Gosh, of course,” Bob agreed.

“However, I think there is only one way to find out,” said Reston. “We’ll go back to that cavern where Ben and Waldo were digging and see if we can find out where they went. But first, I think one of you boys had better go back to the ranch and call the sheriff. We’re going to have evidence to show him.”

Jupiter nodded. “I think Pete had better go.”

Pete’s face fell. “Just when we’re going to finish the case!” he protested.

“Jupiter is right,” Reston said. “Bob’s leg isn’t in good shape, and I want Jupiter with me. Besides, I can see that you’re the fastest, Pete. On a team, each man has to do what he does best.”

Still reluctant, but pleased with the tribute to his athletic prowess, Pete obeyed. He slipped quietly out of the cave, and began to run at a steady pace towards The Crooked-Y ranch house.

Inside the cave, Jupiter, Bob and Sam Reston walked quickly through the tunnels until they stood in front of Old Ben’s secret cavern. Reston moved the boulder, and stepped into the cavern.

The little room was empty. But in the far wall, they found Old Ben and Waldo’s exit tunnel. It was another man-made mine shaft, and it angled sharply upward. With Sam Reston in the lead, his pistol ready, they started through the tunnel. Jupiter marked another trail of chalk question marks.

“We’re heading towards the north ridge of the mountain,” Bob said as they advanced. “That’s where the book says Old Ben and Waldo have their cabin.”

“That is to be expected, Bob,” Jupiter observed. “They opened an old mine shaft close to their cabin so there would be less chance of being observed.”

Reston suddenly stopped. Ahead, the shaft ended in a wall of rocks. Bob noticed footprints on the ground that seemed to go straight into the wall of stones. Reston bent close. He leaned against a boulder and moved it out of the way. Then he moved two more large stones until there was a small passage.

The detective crawled into the passage. For a moment his feet were visible to the boys, and then they vanished. Bob and Jupiter peered into the hole, then quickly scrambled through.

They stood in the clear night behind a thick cover of trees and bushes on the north ridge of Devil Mountain.

“No one would notice a hole that small in the mountain,” Reston observed. “Come on, boys, but stay behind me.”

The detective advanced cautiously along the ridge between the valley and the sea. In a minute they saw a gleam of light in the window of a small cabin. They crept quietly up to the window and looked in. Old Ben and Waldo sat at a bare table, a pile of small stones between them!

His pistol in his hand, Sam Reston opened the door of the cabin.

“Claim jumpers!” cried Old Ben in his high, cracked voice. “Get ’em, Waldo!”

Sam Reston levelled his pistol. “Just sit where you are, Waldo.”

The tall old prospector was half out of his chair. He slowly sat down again.

“The maverick’s got the drop on us, Ben,” Waldo said.

“We gonna let him get away with claim robbing?” Old Ben demanded.

“No one fights fair no more, Ben,” Waldo complained.

The two old men glared furiously at Reston. Then Old Ben’s wild red eyes fixed on Bob and Jupiter.

“Those boys!” he cried. “I told you they was fixin’ to cause trouble, Waldo! We should have taken care of them!”

“I guess you were right,” Waldo agreed.

Old Ben waved his arms wildly. “You mavericks can’t get away with this, you hear? Always get claim jumpers, yessir. Hang ’em high, that’s what we do!”

“The mine’s ours,” Waldo insisted, touching the small pile of rough diamonds on the table.

“Is that why you had to sneak into the cave?” Reston demanded. “Is that why you dug at night and closed that cavern every time anyone came?”

Old Ben’s eyes grew cunning. “A rich strike, yessir. Got to keep it quiet. Word get out, we got a stampede on our hand. No sir, we keep it quiet.”

Bob said hotly, “You wanted it quiet because this land belongs to Mr. and Mrs. Dalton! The diamonds are theirs!”

“We been prospecting that cave almost twenty years,” Waldo protested. “We found the diamonds, we dug ’em out. They belong to us, you hear me, boy?”

All this time Jupiter had said nothing. He was looking intently around the cabin. He was intrigued to see that it contained a radio, a bookcase full of books, and stacks of newspapers. He picked up one of the newspapers and studied it.

Old Ben’s red-rimmed eyes grew even more shrewd.

“Tell you what, there’s enough for everyone, right?” he said in his high voice. “Sure, plenty to go around. Now, we’re not so greedy. Tell you what, we’ll split with you, eh? A quarter of these stones here, and you can dig with us in the mine, eh? Lots more stones in there. A bonanza!”

Suddenly Jupiter spoke up. “There are no more stones, Mr. Jackson, or only a few, and you are quite aware of that.”

Everyone turned to stare at Jupiter.

“This cabin is not entirely consistent with your pose as two eccentric old prospectors living in the past,” Jupiter went on.

“Gosh, Jupe, what do you mean?” Bob exclaimed.

“He means these old codgers are partial fakes,” Sam Reston said, “which I suspect is true. But how did you reach that conclusion, Jupiter?”

Jupiter pointed to the radio. “A portable radio scarcely fits in with the picture of two crazy old men with nothing on their minds but the past. And the books in this bookcase indicate an alertness and interest in the modern world they aren’t supposed to have. I would say they have found the people in the area a soft touch, contributing to their grubstake without asking any questions. And I am also certain that they were aware that they had not found a diamond mine.”

“How do you figure that, Jupiter?” Reston asked.

Jupe indicated the bookcase. “Four of the books in that bookcase are about diamonds, and all four are quite new. In addition, this newspaper contains a full account of the San Francisco diamond robbery from the museum. It is dated a year ago, and the story is circled in pencil. It’s a San Francisco paper, so they must have obtained it specially.”

So!” Reston turned to the two old men. “What do you have to say to that?”

Old Ben and Waldo looked at each other. Finally Old Ben shrugged. When he spoke this time his voice did not sound at all eccentric.