“Yeah, over there. It goes away from the dirt road and off around that hill.”

They all saw the narrow trail that cut through the chaparral and disappeared among low oak trees around the slope of a hill.

“The shack!” Diego cried. “I forgot about it! There’s an old line shack back in there, for the vaqueros on roundup in the old days. It’s just boards and tin. I haven’t been near it for a long time.”

“Was it there in Don Sebastián’s time?” Jupiter asked.

“Oh, yes. At least, Pico told me there’s always been some sort of shack there. In the old days, it was an adobe room.”

“Almost hidden, not used much, and the path to it can be seen from Condor Castle!” Jupiter exclaimed, staring across the arroyo. “That could be the place!”

They climbed down from the giant rock, sinking into the soft earth as they slid down the lower slope and crossed the mound above the arroyo.

Jupiter looked nervously at the overflowing dam.

“I assume the dam will hold,” he said. The unathletic leader wasn’t the world’s greatest swimmer.

“It always has,” Diego said. “Of course, it’s pretty old.”

“That’s real encouraging,” Pete muttered.

On the other side of the muddy road, the boys followed the narrow trail through low oaks and thick chaparral. It was heavily overgrown from lack of use. Crossing the rocky shoulder of a hill, the path led into a small canyon nestled between two bigger hills. The canyon was dark and shadowy on the grey day.

“There, fellows!” Diego pointed.

A tiny, ramshackle hut was tucked in under a massive rock overhang, almost invisible behind trees and high brush. The flat roof was made of thin, rusted sheet metal and the walls were of rough-hewn boards with gaps between them. The door came off as Diego opened it and crashed to the ground in a cloud of dust. The sheltering rock overhang had kept the shack and the ground around it dry.

Inside, there was a single small room with a dirt floor. Bare planks held up the rough-hewn boards that formed the outside walls, and the sheet-metal roof rested directly on narrow open beams. There was no electricity, no window, and no plumbing. There was also no furniture, but a rusty old stove had once given heat.

“A great place to hide for a couple of years,” Pete said. “I’d hate to live here two days!”

“You might feel differently, Second, if soldiers were chasing you, and you had a valuable sword people wanted to steal,” Jupiter observed. “But I admit it’s pretty bare.”

“Too bare, First,” Bob said. “No closets, no cupboards, no nooks, and no crannies! There’s nowhere to hide anything.”

“Gosh,” Diego said as he looked at the bare, open walls and ceiling, “Bob’s right. There’s nowhere.”

“The floor?” Pete suggested. “Don Sebastián could have buried the sword here, and left the spot unmarked.”

Jupiter shook his head. “No, if he’d buried the sword in here, the fresh dirt would have shown for a long time. I don’t think he’d have risked that. However — ”

The stocky First Investigator was looking thoughtfully at the rusted old stove. Its pipe went up through the tin roof, and its feet rested on a slab of stone.

“I wonder,” Jupiter said, “if this stove can be moved easily?”

“Let’s find out,” Pete said.

The tall Second Investigator gave the stove a push. It was solid and heavy, but it moved. It wasn’t attached to the flat stone under it.

The pipe was jointed with a short section just above the stove. “Slide up that short piece,” Jupiter ordered.

Pete pushed at the short section of pipe.

“Gosh, it’s rusted tight,” he said.

“It wouldn’t have been in 1846,” Jupiter exclaimed. “Break it off if you have to.”

With the help of some tools from Bob’s saddlebag, Pete broke the rusty stovepipe just above the stove. Then, all together, the four boys heaved the stove off its slab. Pete kneeled and tried to move the stone.

“Ooofff,” he grunted. “It’s too heavy, First.”

“Over there.” Diego pointed to a wall. “That beam of wood looks loose.”

Jupiter helped Diego to rip the beam from the wall while Bob and Pete rolled the stove close to the slab. Pete dug down beside the slab until he found the bottom, then scooped out a hole big enough to let the end of the beam slip under the edge of the slab. With the middle of the long plank resting against the stove as a fulcrum for their lever, the four boys heaved their weight down on the other end of the wood.

The flat stone slab flipped up and fell away, revealing a small, deep hole under it! Diego bent over the dark hole.

“I see something!” he cried even before Bob turned on his flashlight.

He reached down into the hole as far as he could and pulled out some short lengths of frayed rope, a heavy sheet of paper that was brown with age, and a long, rolled-up piece of canvas that had been tarred black. Diego looked at the browned piece of paper.

“It’s in Spanish,” he said. “Fellows! It’s a proclamation from the US Army dated 9th September, 1846! Something about rules for the civilian population.”

“That tarred canvas is just the size for wrapping a sword,” Jupiter realized. He began to unroll the canvas with trembling hands.

“It’s empty!” Pete groaned as the canvas opened on nothing.

“Diego, is there anything else down there!” Jupiter said.

Bob stood over the hole with his flashlight while Diego looked inside and felt around with his hand.

“No,” Diego said, “there’s nothing I… Wait! I’ve got something! It’s… It’s just a small rock.”

Dejected, Diego brought his hand out and opened it to show a small, dusty rock. He rubbed it clean against his shirt. Now the small, almost square stone was a deep and glittering green!

“Is it…?” Bob started to ask.

“An emerald!” Jupiter cried. “The Cortés Sword must have been in that hole! That must be where Don Sebastián had it hidden at first. When he escaped from Sergeant Brewster, he got the sword and hid it somewhere else. Maybe someone had a hint that the sword was here, or maybe he just didn’t think this shack was safe enough.”

“He was right,” Bob said. “We spotted it pretty fast.”

“Then he wouldn’t have tried to hide out here himself,” Diego said. “This can’t be the place.”

“No,” Jupiter agreed, “but the emerald means that we’re getting closer. Now we know that Don Sebastián had the sword out here. It wasn’t smuggled to him. Sergeant Brewster’s story has one more lie in it. No, the sword was here until Don Sebastián came for it that night and hid it somewhere else! He hid the sword, and himself, and he had to do it fast.”

“Jupe?” Pete said suddenly. “What’s that noise?”

They listened. It was a loud drumming sound from somewhere outside. Almost a roar like an avalanche…

“Rain!” Bob exclaimed. “It’s hitting everywhere except here, under the rock overhang. Wow, it’s a real deluge.”

“No,” Pete said, “I mean that other sound. Hear it?”

Jupiter shook his head and Bob shrugged. But Diego heard it.

“Voices!” Diego whispered. “Someone’s out there.”

They slipped out the doorway and crouched behind the thick bushes that hid the shack. The three tramp-like cowboys were crossing the small canyon in the downpour. Their voices floated through the heavy rain.

“… saw ’em come this way, Cap. Four of ’em.”

“… keep followin’ this trail.”

The men moved on past the shack without seeing it under the overhang, and vanished around the next hill. Jupiter stood up.

“They won’t be back for a while,” he said. “We’ll get back to Condor Castle before they spot us. Come on.”

But this time Jupiter was wrong! The boys were still crossing the open canyon when voices shouted behind them!

“You four!”

No one had to tell the boys to run!