That was agreeable to Doc. It seemed very welcome to Princess Monja, too.

They set off at once.

"This has the appearance of having been built and used centuries ago," Doc offered.

Princess Monja nodded. "It was. When the Mayan race was in its glory, rulers of all this great region, they built this tunnel and the pyramid outside. A hundred thousand men were kept working steadily through the span of many lifetimes, according to the history handed down to my father and myself."

Johnny murmured wonderingly. Johnny had been taking notes on bits of little-known Mayan lore, intending to write a book if he ever got time. He probably never would.

Princess Monja continued. "This has been a guarded secret for centuries. It has been handed down through the rulers of the Mayans in the Valley of the Vanished. Only the rulers! Until a few minutes ago, when the attack came, only my father and myself knew of it."

"But why all the secrecy?" Johnny inquired.

"Because word of its existence might reach the outer world."

"Huh?" Johnny was puzzled.

Princess Monja smiled slyly. "Wait. I will show you why knowledge that this existed would inflame the outside world."

They had reached the upswing in the tunnel, having covered many hundred yards. Doc knew they were far under the wails of the chasm that hid the Valley of the Vanished.

Suddenly Princess Monja halted. She pointed and spoke in a voice low and husky.

"There is the reason! There is the gold you are to have, Mr. Savage. The gold you are to expend in doing good throughout the world!"

Johnny and Monk were staring. Their eyes protruded. They were stunned until they could not even voice astonishment.

Doc Savage himself, in spite of his marvelous self-control, felt his head swim.

It was unbelievable!

Before then, the corridor had widened. It became a vast room. Solid rock made walls, floor, roof.

The rock showed veinings of gold! It was the same kind of rock of which the pyramid was made!

But it was not this that stunned them.

It was the row after row of deep niches cut into the walls. Literally hundreds of thousands of the cupboardlike recesses.

In each was stacked golden vessels, plaques, goblets, amulets. Everything the ancient Mayans had made of the precious yellow metal could be seen.

"This is the storeroom," said Princess Monja in a low voice. "Legend has it forty thousand artisans were continuously employed making the articles, which were then stored here."

Doc, Monk, and Johnny hardly heard her. Sight of this fabulous wealth had knocked them blind, deaf, and dumb to everything else.

For the niches held only a fraction of the hoard here! It lay on the floor in heaps. Great stacks of the raw, rich gold! And the treasure cavern stretched far beyond the limits to which their wick-in-a-bowl lamp projected light.

Doc shut his eyes tightly. His bronze lips worked. He was experiencing one of the great moments of his life.

Here was wealth beyond dream. The ransom of kings! But no king could ever pay a ransom such as this! It was enough to buy and sell realms.

Doc's brain raced. This was the legacy his father had left him. He was to use it in the cause to which his life was dedicated — to go here and there, from one end of the world to the other, looking for excitement and adventure; striving to help those who need help; punishing those who deserve it.

To what better use could it be put?

Pretty Princess Monja, in whose life here in the Valley of the Vanished, gold meant not a thing, spoke.

"The metal was taken from deeper within the mountain. Much yet remains. Much more, indeed, than you see stacked here."

Gradually, the three adventurers snapped the trance which had seized them. They moved forward.

Ahead of them ran the stone pipe which fed water to the pyramid pool.

Monk started to count his steps the length of the treasure vault. He got to three hundred and lost track, his faculties upset by looking at so much gold. The piles seemed to get higher.

Their route narrowed abruptly. The tunnel floor slanted upward steeply. A couple of hundred feet, they nearly crawled. Then they came to a tiny lake, where the stone pipe ended. This was in a small room.

The walls of this room had been but partially hewn by human hands. Water had excavated a great deal. The stream ran on the floor.

Ahead stretched the cavern. It seemed to go on infinitely.

Doc now realized the cavern was partially the work of the underground stream. It probably extended for miles. Originally, the Mayans had found gold in the stream mouth. They had ventured into the cavern, knowing it must have washed out of there.

And they had found this fabulous lode.

Princess Monja put a query. "Do you wish to go on?"

"Of course," Doc replied. "We are seeking an outlet. Some manner in which the Mayans can escape starvation or surrender."

They continued into the depths. The air was quite cool. There was a wide path, hewn by human hands.

Sizable stalagmites, like icicles of stone growing upward from the path's middle, showed convincingly that ages had passed since feet had last trod here.

Often, great rocks near blocked the trail. They had fallen from the ceiling. And everywhere, gold inlaid the stone in an ore of fantastic richness.

Doc and his friends had lost interest in the ore. After the vast riches in the storage cavern, nothing could excite them much.

Upward wound the underground stream. Two hours, they toiled ahead. By then, they had gotten beyond the area of gold ore. There was no path now. No gold glistened in the stone.

The way grew more tortuous. The character of the rock walls changed. Johnny stopped often to examine the formations. Monk ranged off into every cranny they came to, hoping to find an exit.

"There is one, somewhere!" Doc declared. "Not far off, either."

"How can you tell?" Princess Monja wanted to know. Doc indicated the flame of their torch. It was blowing about in a manner that showed a distinct breeze.

Johnny dropped behind as far as he could, and still kept them in sight. In darkness as he was, he knew he would be more liable to discover an opening into the outer sunlight.

For the same reason, Monk went ahead. The hairy anthropoid of a fellow had more confidence in his ability to get over unknown ground.

Doc was himself an interested observer of the formations of rock through which they were now passing. A villainous, yellowish-gray deposit attracted him. He scratched it with a thumbnail, and burned a little in the torch flame. It was a sulphur deposit.

"Sulphur," he repeated aloud. But no solution to their troubles presented.

They came soon to a rather large side cavern. The formation was mostly limestone here.

While they waited, Johnny ventured up the side cavern to explore for an opening. Five minutes passed. Ten.

Johnny returned, shaking his head.

"No luck!" He shrugged.

He was juggling a white, crystalline bit of substance in a hand.

Doc looked at this. "let me inspect that, Johnny!"

Johnny passed it over. Doc touched the end to his tongue. It had a saline taste.

"Saltpeter," he said. "Not pure, but pure enough."

"I don't understand," Johnny murmured.

Doc recited a formula: "Saltpeter, charcoal, and sulphur! I noticed the sulphur back a short distance. We can burn wood and get the charcoal. What does that add up to?"

Johnny got it: "Gun powder!"

Even as he exclaimed the word, they received fresh cause for elation.

Monk had gone ahead a hundred yards, exploring. His howl of delight came to them.

"I see a hole — "

Monk's hole proved to be a rip in solid rock of considerable size. Sunlight blazed through.

Doc, Princess Monja, Johnny, and Monk clambered up to it. They found crude steps, proof the ancient Mayans had known of this exit. They sidled cautiously outside, squinting in the sun glare.