“They’re gone!” Bob exulted.

“Not for long,” Jupiter declared. “They’ll crawl out downstream, and be between us and the county road! Let’s move!”

Pete led the way up the slope to the great rock of Condor Castle. They climbed up over it and started down the other side. On both sides of the ridge, mud and boulders had slid down in the heavy rain, exposing new boulders and rocky outcroppings below Condor Castle.

“Wow, the mud’s sliding everywhere!” Pete exclaimed as he led the way down the steep, slippery slope.

The athletic Second Investigator leaped over a large row of exposed boulders. The others climbed up the boulders behind him—and stopped, gaping.

Pete was gone!

Pete had vanished as if the ridge itself had swallowed him up!

“Wha-what?” Diego stammered. “Where did he go?”

“Pete!” Bob cried.

“Second! Where are you?” Jupiter called frantically.

They anxiously searched the slope with their eyes, but nothing moved. Listening hard, they finally heard something. A voice that seemed to come from nowhere!

“Fellows! Down here!”

It was Pete — and his muffled voice seemed to come right out of the ridge!

“Where are you, Pete?” Diego called.

“Down here! Look right in front of those big boulders!”

The three boys jumped down in front of the exposed boulders and saw a long, narrow hole in the slope! A hole that was all but invisible until they were right on top of it! It hadn’t been there before.

“A mudslide must have uncovered the hole!” Bob realized.

Jupiter bent down to the long, narrow slit in the ridge.

“Second? You need help to get out?”

“I don’t want to get out!” the disembodied voice of the Second Investigator said. “It’s a kind of cave, Jupe! There’s loose rocks down here. We could block up the hole and those cowboys would never spot us! Come on down.”

The three boys on the slope looked at each other.

“Well — ” Jupiter hesitated.

“Come on!” Pete urged. “It’s dry and roomy, and those guys could come back anytime!”

That reminder was all the other three needed. Bob slipped down into the narrow hole first. Jupiter followed, grunting with the effort. The stout boy stuck halfway into the narrow opening!

“I… I can’t fit down — ” he said, red-faced.

From inside the cave Bob said, “Diego, push him! We’ll pull!”

Hands grabbed Jupiter’s legs. Out on the slope, Diego gripped the stout leader’s shoulders and pushed. With a loud sound, almost like the popping of a cork from a bottle, Jupiter slid down and vanished. Diego jumped through behind him.

Bob already had his torch on in the dark hole.

“Gosh!” Diego said as he looked around. “I never knew there was a cave here.”

The light showed a small, rocky space about the size of a one-car garage, with a low ceiling and loose rocks and boulders strewn around the floor. The cave was still dry despite the heavy rain now coming through the hole in the ridge. It had obviously been open only a very short time.

“Shine the light around, Records,” Jupiter commanded.

The small, low cave extended back some ten or fifteen feet and ended in a pile of loose rocks that rose to the ceiling. Jupiter examined the exposed entrance and slowly nodded.

“It looks as if it was covered up sometime in the past, fellows, probably by an earthquake. Rocks rolled down the — ”

“Never mind how it got covered up,” Pete exclaimed nervously. “A mudslide opened it, and those cowboys could spot the hole the same as we did! Let’s block it up!”

“There’s plenty of loose boulders,” Diego pointed out.

The four of them rolled and heaved at the biggest rocks they could move, and finally shut out the grey light of the late afternoon. With the opening closed off, no more rain came down into the cave. The four boys sat back and grinned at each other.

“We’ll wait a few hours,” Jupiter decided, “and by then those cowboys should have given up and gone.”

“I still wonder who they are?” Bob mused.

“They must have some connection with Mr. Norris,” Diego said grimly, “or why would they have stolen Pico’s hat and put it out near that campfire?”

“If they did,” Jupiter said. “We only know that they were looking hard for the car keys that Bob and Pete found in the barn. I wonder why we haven’t seen them with a car?”

“Well,” Pete said, “they sure want those keys, so the keys must prove something bad.”

“Yes,” Jupiter agreed. “Perhaps they — ”

“Ju-Ju-Jupe!”

It was Bob who began to stammer. He was shining his torch towards the rocks at the rear of the cave.

“That… that… rock,” Bob went on “It’s got… it’s… got — ”

“Eyes!” Diego gulped. “Eyes and… teeth!”

“A skull!” Pete moaned.

Jupiter stared at the pile of rocks. He blinked, and then his eyes seemed to light up. He hurried towards the rear.

“It is a skull!” he said. “Dig around, fellows!”

Pete said unhappily, “Here’s some more bones! He must have been buried in here by the quake!”

“Here’s some kind of cloth under the rocks,” Bob cried.

“A button!” Diego said. He held up a round piece of blackened brass. “It’s a US Army button!”

“This man didn’t get buried in here — at least not while he was alive!” Jupiter exclaimed. “There’s a hole in the skull! The guy was shot!”

The excited First Investigator looked at the others. “I think we’ve found the nest of the eagle! Where Don Sebastián planned to hide — and to hide the Cortés Sword! A cave right under Condor Castle would fit all the clues! And José would have known about it!”

Diego asked, “You think this soldier is one of the three who were after my great-great-grandfather?”

“I think so,” Jupiter said. “And I think there must be more to this cave!”

“This pile of rock is loose,” Pete said, testing it. “Maybe it blocked off part of the cave at the same time that the entrance to the cave was buried?”

Jupiter nodded in agreement.

Pete groaned. “Okay, let’s start digging!”

The boys went quickly to work, pulling away the fallen rocks and throwing them aside. It was long, slow work. The more rocks they pulled loose, the more rolled down to fill up the spaces. But slowly and steadily the boys inched further ahead. The wall of loose rock grew thinner, until…

“I see a space!” Bob cried. He shone his torch ahead. “Yes! There’s some kind of passage behind this pile of rocks!”

They pulled away more stones and revealed a dark, narrow passage just barely large enough for Jupiter to fit through. Holding his torch, Bob crawled into the dark passage first. It went straight back. A few minutes later, Bob found himself in a cavern some three times the size of the small outer chamber.

“It’s a big cave!” Diego said as he crawled out of the passage and stood up.

The larger cave was about twice as high as the outer chamber, with sheer, slick sides of solid stone and a solid stone floor with a few outcroppings of rock.

“We must be right under Condor Castle,” Bob guessed.

“What a place to hide!” Pete exclaimed. “You could block up the outside entrance and the passage real easy.”

“With someone outside to bring in food and water,” Diego added, “a man could stay in here safely for a long time.”

“If he made it in here unseen, and had time to block the entrances,” Jupiter said. “I don’t think Don Sebastián did.”

He pointed silently to the left of the passage. Bob shone his light. There was a second skeleton! It was lying on its back behind one of the outcroppings of rock. Blackened brass buttons lay around it, and there was a rusted old rifle at its side.

“He must have tried to take cover behind the rock,” Pete said. “I guess it’s the second of those soldiers.”

“And there’s the third!” Jupiter exclaimed.

Bob’s light had swept ahead to reveal a third skeleton lying face down in the centre of the cave. There were brass buttons lying around again, and also the remains of rotted leather boots and a crumbling leather belt with a pistol holster. A Mexican War-style revolver lay inches from the fingers of the skeleton’s right hand.