“Yes, I thought about that.”

“In addition,” Jupiter continued, “did you notice how his face never seemed to move? How he never showed any expression?”

“Sure I did, but — ”

“I’m convinced that our captor was wearing a mask, Pete!” Jupiter said triumphantly. “One of those flesh-coloured rubber masks that fit over the whole face. In addition, he spoke very little. I think he was afraid we might recognize his voice.”

“I didn’t. Did you, Jupe?”

“No,” Jupiter admitted. “But I’m sure of one thing, anyway. He didn’t want to harm us seriously, or he wouldn’t have just imprisoned us in here.”

“Just imprisoned us!” Pete objected. “Isn’t that bad enough?”

“He could have done a lot worse,” Jupiter pointed out a little grimly. “In here we’ll be found sooner or later after we’re missed, and he knows that. There’s plenty of air. All he wanted was to have us out of the way for a short time, probably just to-night. Which means that we have to hurry and find our way out of here.”

“Do you think it’s safe yet, Jupe? Why don’t we just let someone find us?” Pete asked.

“I’m convinced that the mystery has to be solved to-night,” Jupiter insisted. “If we wait, it will be too late. Since we can’t get out the way we came in, we have to see if going in the other direction leads us to some exit. Come on.”

Pete followed Jupiter down the narrow passage. The tunnel continued straight ahead without any cross passages for what seemed like miles. Then suddenly the boys stopped and stared at each other in dismay. In front of them was another fall of rock. The passage was blocked at this end, too!

“Golly, Jupe!” Pete cried. “What do we try now?”

“I hadn’t thought we would be blocked in so completely,” the First Investigator said, and for the first time his round face looked worried. “It doesn’t fit my deductions at all.”

“Maybe El Diablo has different deductions,” Pete observed.

Jupiter leaned down and carefully inspected the fall of rock. It, like all the others, was not recent. Jupiter bent closer. Suddenly he became excited.

“Pete, this big rock has been moved!”

Pete bent down and looked. From the marks on the floor there was no doubt that the big rock had been moved recently.

Together the boys strained at the boulder. It rocked slightly, but would not roll loose. Jupiter stood up and looked around.

“I think our friend used this passage to enter and leave the cave unseen. If the two of us can’t move it, then there has to be some other way… There! That long steel bar near the wall!”

Pete understood at once. A lever! He grabbed the long bar and inserted it between the stone and the wall. Together the two boys leaned their weight on it and the great stone rolled away.

A gaping hole opened in front of them. Jupiter shone his light into the darkness.

“It’s another cavern,” he reported.

Pete dropped the long bar and both boys scrambled through the opening. They shone their flashlights around.

“Wow!” gasped Pete.

Jupiter just stared.

They were standing in an enormous cavern. In the centre was a great black pool.

The pool glittered in the beams of their flashlights.

Pete swallowed hard. “The pool,” he said in a low voice, “where The Old One lives.”

“So there is a pool,” Jupiter said. “It must have been blocked off a long time ago, but the Indians knew it was in the cave somewhere.”

“And now we know, too, but I wish we didn’t,” Pete quavered. “Let’s find a way out of here quick!”

“Just because the pool is really here doesn’t mean that The Old One actually exists.”

“It doesn’t mean The Old One doesn’t exist, either,” Pete pointed out. “Maybe The Old One’s been blocked off a long time, too. Maybe he’s mad and hungry and just waiting for two smart boys.”

Jupiter glanced around the dark cavern. Shadows in the wall indicated more passages leading from the cavern.

“We’d better try to find a way out,” Jupiter decided. “Light your candle and we’ll test the openings.”

“Now that’s what I like to hear,” Pete said.

He lit his candle and followed Jupiter. They tested two of the passages without success. Pete started to move on, but Jupiter stood still.

“Pete,” he whispered.

Pete followed Jupiter’s gaze. At first he could see nothing.

“There, against the wall,” Jupiter hissed. “It’s… it’s… ”

Then Pete saw it — or rather, him! In a dark recess just inside the second passage, seated against the wall with his legs straight out in front of him was a small man, dressed all in black, with a sombrero on his head, and black boots on his feet. In his right hand the man held an ancient pistol, and his face was grinning straight at the boys.

Except that the face looking at them was not a face at all — it was a skull! And the hand that held the pistol was not a hand, it was five bones — a skeleton!

“Yow!” Pete cried. Both boys turned and ran. They reached the tunnel which had led them into the cavern and tried to scramble through the opening together. Both of them went down in a heap. “Where are we running to, Jupe?” mumbled Pete, on the bottom. “We can’t get out this way!”

“Of course,” replied Jupiter. “We weren’t thinking clearly.”

“I wasn’t thinking, period,” Pete said in a muffled voice. “Maybe you better get off me for a start.”

“I would, but you’re holding my leg,” Jupiter said.

The boys untangled themselves, and sat up on the cold floor of the cavern. They were still shaking, but Pete began to grin.

“Boy, we’re a couple of brave investigators!”

Jupiter nodded solemnly. “We panicked. A natural enough reaction under the circumstances, I believe. The accumulation of dangers resulted in a degree of nervousness that made us lose our rational responses. A skeleton is probably the least dangerous menace we have faced. We were simply at the point of panic.”

Pete groaned. “It’s too bad Bob isn’t here to tell me what you just said.”

“If he was here he’d tell you I said we were so tense from what’s happened that we blew our tops,” Jupiter said.

“You could have said that the first time.”

“I could have, but it isn’t exactly the meaning I wanted to communicate. However, that isn’t what we should be concerned about now. I want to inspect that skeleton.”

“I was afraid you’d want to do that.” Pete followed Jupiter rather unwillingly over to where the skeleton seemed to grin at them from beneath the black sombrero. Warily, Jupe reached out and touched the sombrero. It crumbled into dry pieces.

“Golly!” Pete exclaimed, and touched the black jacket.

The jacket, too, crumbled and fell away from the skeleton. As Pete pulled his hand back, he brushed the bony fingers that held the gun. The fingers snapped off, and the pistol dropped to the floor with a loud, echoing clatter. Pete jumped back, but Jupiter bent closer to the skeleton.

“It’s very old, Pete,” Jupiter observed. “And that pistol is ancient too… I would say that there is very little doubt about it.”

“Very little doubt about what?”

“That this skeleton is El Diablo — the real El Diablo!” Jupiter’s words echoed from the high ceiling of the cavern like some ghostly voice from the past.

“The real El Diablo?” Pete said. “You mean he was in here all the time but no one ever found him?”

Jupiter nodded. “I wouldn’t be surprised if he died the very night he came into the cave. His wound must have been worse than anyone realized. Of course, in those days men often died from wounds we would consider minor today. Medical science has made great progress.”

“But what makes you think he died that night?” Pete asked, puzzled. “I mean, maybe he hid in here for years before he died.”

Jupiter shook his head. “No, I don’t believe so. First, you will notice that there are no signs of any food around the skeleton. He could have drunk water from the pool, although I would guess that the pool is salt water. Anyway, even if he had water there should be some evidence of food: bones, dried seeds, something.”