“Gosh!” Pete whispered. “It hurts my ears.”
Jupiter caught Pete’s arm. “Look!”
Their eyes had adjusted to the bright light inside the cavern, and they could see a figure bending over with a shovel in his hand.
Pete gulped.
The figure suddenly straightened, put down his shovel, and picked up a pickaxe. For a moment he was clearly visible in the light of his electric lantern — a man with white hair and a flowing white beard.
Old Ben Jackson.
“Look,” Jupiter whispered. “It looks like another rock fall.”
“It’s a big one,” Pete whispered back.
“You see how those breaks in the rocks are sharp and clean?” Jupiter pointed out. “That fall happened very recently.”
Old Ben continued his work at the fall, unaware of the eyes watching him. The old prospector swung his axe with vigour and surprising strength for a man of his age. Then he put it down again, and picked up the shovel.
“Jupe!” hissed Pete. “Look at his eyes.”
The eyes of the old prospector gleamed wildly in the light of his electric lantern, just as they had the previous night when the old man had warned them against The Old One.
“Gold fever,” Jupiter said softly, “or, in this case, diamond fever. I’ve read that prospectors often get like that when they think they have a strike. Nothing can get in their way or stop them.”
“Gosh,” Pete whispered.
Old Ben turned again to the wall and dug steadily at the fallen rock loosened by his pickaxe. He shovelled it into a kind of tilted sieve. Every few minutes, while the boys watched, he bent down and picked something out of the dirt. Each time, he examined the object, laughed wildly, and put it into a small leather bag near the electric lantern.
“Are they diamonds?” Pete whispered.
“I expect so,” Jupiter responded in the same low voice. Old Ben was so involved in his work that he probably wouldn’t have heard the boys if they had spoken normally, but they were taking no chances.
“Then he has found a diamond mine,” Pete said.
Jupiter was staring at the rock fall, his round face furrowed with thought.
“It looks that way, Pete, only — ”
“What else could it be? He’s struck a diamond mine, and he knows it’s on Crooked-Y property. If anyone found out about it he’d at least have to share the diamonds with the Daltons, wouldn’t he? Maybe legally they all belong to Mr. and Mrs. Dalton. So he only digs at night, and he scares everyone away from the cave!”
Jupe nodded slowly. “I guess you’re right, Pete. That explains everything except — ”
“Except why the cave moans,” Pete interrupted. “And what makes it stop when anyone comes inside.”
“I wasn’t thinking of that,” Jupiter said, “but I think I can explain why the moaning stops. You see, the sheriff and Mr. Dalton must have found this mine shaft all right. Only they didn’t find the place where Old Ben is working.”
As Pete opened his mouth to ask a question, a bell began to ring insistently in the hollow cave.
Old Ben dropped his shovel and moved with amazing speed to a small box near his lantern. He touched something on the box and the clanging bell stopped. Then he picked up his lantern and the small leather bag and headed straight for the hole in the wall where Pete and Jupiter were crouching.
“Quick, Pete!” Jupiter whispered urgently.
The two boys scrambled back to hiding places behind the loose mounds of rock in the shaft. They were none too fast. They had barely got out of sight when Old Ben came through the hole in the wall. The old man laid down his lantern and leather bag, and picked up a long steel bar the boys had not noticed in the floor of the shaft.
At that moment the moan began once more.
“Gosh, Jupe,” Pete said. “That’s what you meant! No one could tell there was a hole in that wall.”
The large boulder fitted tightly into the gap as if it had always been there.
“Right,” Jupiter whispered, “and the blocking of the hole stops the moaning right away. That bell must be the signal from whoever is watching up on the mountain. I think it means someone is coming into the cave.”
“Maybe Bob got scared and went for help,” Pete said. “I hope.”
Old Ben was pacing up and down in the mine shaft, muttering to himself. He didn’t even glance towards the rocks where the boys were hiding. Then, suddenly, the old man switched off his lantern. For a moment there was no sound in the dark mine shaft; then the boys heard the pacing and muttering begin again. They waited tensely in their hiding place.
In the darkness, Pete tried to sort out everything he had learned that evening. There were still questions he wanted to ask Jupiter, but Pete thought he understood most of the answers to the mystery of Moaning Valley.
Old Ben was digging secretly in the cave. Up on the mountain someone was on guard. The moaning sound was produced by the wind blowing through the narrow opening of the prospector’s secret cavern. When someone came to the cave, the guard signalled with the bell and Old Ben closed up the hole. The moaning sound stopped and there was no clue to what caused the moaning.
Pete felt quite pleased with himself for figuring it all out. He had answered all the questions himself… or had he? Who, for instance, was the fake El Diablo who had captured them? And how did he fit into the puzzle? Was that what Jupe had been referring to when he said something was still unexplained?
“Pete!” Jupiter’s voice whispered in his ear. “Someone is coming!”
Pete was so startled he almost lost his balance. He grabbed at the big rock in front of him, and a small stone rolled to the ground. Had Old Ben heard the noise? Pete held his breath.
A moment later he saw a bobbing light approaching.
“Waldo?” Old Ben’s voice said from somewhere nearby.
“Yup,” a voice replied from behind the bobbing light. “They’s two of ’em coming in the cave, Ben. We best skedaddle.”
Old Ben’s lantern came on, and Jupiter and Pete could see the tall, thin figure of Waldo Turner. The boys crouched as low behind the rocks as they could get. The two old men stood less than ten feet from them now.
“You sure they’re comin’ in?” Old Ben asked.
“I’m sure. Too dang many people foolin’ around this cave the last couple days,” Waldo replied.
“Jumping bobcats!” Old Ben exclaimed. “And I figure not more’n a few more days’ work ’fore we’re finished. Well, no sense gettin’ careless now. We better get on out.”
“We better,” Waldo agreed.
It was clear that Waldo Turner was the man on watch on top of Devil Mountain. After giving the alarm, he had come down by some secret passage from the top.
The boys watched the two old prospectors move the boulder away from the hole, pass quickly through, and lever the rock back into the hole from the inside. Then there was silence in the pitch-black mine shaft.
“Where did they go, Jupe?” Pete whispered.
“There must be an exit from that cavern to the outside of the mountain. There would have to be. The wind wouldn’t be able to make that moaning sound if it couldn’t blow through from the other side. It’s probably one of those old mine shafts that are supposed to be sealed up. I’ll bet Old Ben and Waldo knew just where those shafts were and unsealed one.”
“How come the sheriff and Mr. Dalton don’t know it’s there?” Pete asked.
“It’s probably concealed,” guessed Jupiter. “There has to be another entrance up high on the mountain, too, for Waldo to get down here so fast. There are probably quite a few hidden entrances. However, I think it’s time we went for help.”
“Let’s go!” Pete agreed fervently.
The boys switched on their flashlights and walked rapidly back along the mine shaft. By retracing their steps, they soon reached the first large cavern they had entered the previous night.
As they hurried towards the tunnel that would lead them outside, two figures leaped out of the shadows. Strong hands closed on Pete’s arm.
“Got you!” a harsh voice grunted.
Pete gulped in fright as his light shone up into the long, scarred face of the man with the eye patch.
“Run, Jupe!” Pete cried.
At the same instant, a flashlight was suddenly beamed on Jupiter by the second man.
Jupiter braved it out. “I doubt that you would care if I were hurt. I suggest you let us go. We have friends here.”
The man laughed. “Spunky, aren’t you?… Why don’t you come over here where we can have a talk.”
“Don’t, Jupe!” Pete cried.
And then a familiar voice spoke from behind the flashlight of the second man.
“It’s okay, fellows. Mr. Reston is a detective!”
The voice was Bob’s and his face was one big grin when he came out into the light and saw the astonished looks of his partners.
“I started for the ranch to get help after I saw that the man in the Nevada car was going into the cave,” Bob explained. He went on to describe his sudden hunch that Old Ben and Waldo were involved in the mystery of Moaning Valley. “After the Nevada car passed me I was scared and ran right into Mr. Reston here.”
“Sam Reston,” the man with the eye patch, introduced himself. “I’m a detective, boys, working for an insurance company. When your friend here told me of his suspicions about Old Ben, I decided to come back to the cave with him instead of going all the way to the ranch for help.”
“Mr. Reston thought you might need help right away,” Bob explained.
“I did,” Reston said, “because the man I’m after is very dangerous. Bob and I tried to get into the cave unseen. It took us some time, and I think we were seen anyway.”
“You were, Mr. Reston,” Jupiter said, suddenly recovering his voice. The First Investigator told Bob and Mr. Reston about everything he and Pete had seen in the cave.
Reston nodded. “I was afraid we’d been spotted. But they can’t have gone far, and that bag you saw probably contains the diamonds I’m after.”
“What diamonds?” Pete burst out.
“That’s the job I’m on, boys,” Reston explained. “I’m trying to find a very clever jewel thief who stole a fortune in diamonds. His name is Laslo Schmidt, and he is known all over Europe. I followed his trail here to Santa Carla just a week ago. Then I heard about Moaning Valley and El Diablo’s Cave, and I had the idea that the cave would be a good place for Schmidt to hide. Only I haven’t found a trace of him.”
“Gosh,” Pete said, “if you followed his trail here, why couldn’t you spot him?”
“Because I have no idea what he looks like now,” Reston told them. “You see, boys, about five years ago Schmidt left Europe in a hurry. The International Police, Interpol, learned that he had come to America and assumed a new identity. But that was all they could find out. Schmidt is a master of disguise and impersonation. He could act the part of almost anyone and make you believe it.”
Jupiter had his faraway thoughtful expression. “And he stole some diamonds insured by your company, Mr. Reston?”
“Yes, about a year ago. He hadn’t stolen anything since he left Europe, and the police thought that he had given up, or perhaps even died. But when the diamonds were stolen we knew at once that Schmidt was the thief. The way it was done, it could have been no one else.”
“The modus operandi, or method of operation is very important,” agreed Jupiter. “That is how most criminals are caught, especially professional thieves. A thief can never really change his way of committing a theft except in minor details.”
“That’s right, Jupiter,” Reston acknowledged. “The theft was obviously the work of Laslo Schmidt, and we realized that he had been simply biding his time. It became clear that he had spent his years in this country establishing a new identity. So now he is actually two men: Schmidt the thief, and some other person who is perfectly normal and above suspicion.”
“And you don’t know what this other identity is,” Bob put in quickly. “It could be anyone around here.”
Reston nodded. “Exactly, Bob. I traced him through the sale of two of the diamonds. First to Reno, Nevada, and then here.”
“Nevada!” Pete and Bob both exclaimed at once.
“Gosh,” Pete added, “we thought you were driving that Nevada car that forced us over the cliff.”
“No, boys,” Reston explained. “I was on my way to Moaning Valley when I saw your bikes at the edge of the pass. I stopped to see what was wrong, and would have rescued you, but then I saw those other people coming and knew you’d be okay. At that time I didn’t want to reveal my presence here. You see, I think Schmidt spotted me in Nevada. I tried to fool him by putting on this eye patch and pasting a false scar on my face before coming to Santa Carla. I’m not sure my disguise was successful, though.”
“That’s why you’ve been sort of hiding?” Bob asked.
“That’s right. I didn’t want Schmidt to know I was still on his trail.”
While Reston had been talking, Jupiter had been staring off into the dark spaces of the cavern and biting his lip. Now an eager gleam came into his eyes.
“The diamonds he stole,” Jupiter said slowly. “There is something special about them, isn’t there, Mr. Reston?”
Reston looked at him in astonishment. “Why, yes, Jupiter, there is. You see, they weren’t stolen from any jewellery company or store. They were taken from a special display at a museum in San Francisco. They — ”
“—are rough diamonds!” Jupiter completed the sentence for him. “They are uncut, exactly as they came from the diamond mine, correct? They are also industrial diamonds.”
“I don’t understand how you know,” Reston said, “but you’re right about their being rough diamonds. Only a few are just industrial stones, though. You see, the display was made up of diamonds from all over the world, just as they came out of the ground. Because they look like ordinary rocks, and because they were in a museum, they were not very well-guarded. Schmidt had no trouble stealing them. Most of them are gemstones, very valuable and just about unidentifiable since they are rough. But how did you know, Jupiter?”
“Because I found a rough diamond here in the cave,” Jupiter said, “and because I think Old Ben and Waldo have found the rest of them!”
“Then the stones really are in the cave!” Reston exclaimed.
Jupiter nodded solemnly. “I think your Laslo Schmidt hid them here right after he stole them. He probably planned to keep them hidden until everyone gave up the chase. Only Old Ben and Waldo, prospecting secretly in the cave as they have probably been doing for years, found them and thought that they had uncovered a diamond mine!”
“But there are no diamond mines in this area,” Reston pointed out.
“No, sir, but Old Ben and Waldo have always believed that there are diamonds here. I remember Mr. Dalton said they have been looking for precious stones as well as gold and silver. The diamonds Schmidt stole look exactly as they would if they had just been dug up, don’t they?”