In that Doc's reasoning could not have been more accurate had he witnessed the arrival of the enemy.

At this juncture Long Tom ran up.

"The Red Death!" he puffed. "They're collapsing with it all over the city!"

Doc administered an opiate to the first Mayan to be stricken to ease his pain, then visited a second sufferer. He questioned each closely on where he had been, what he had eaten. Four more Mayans he asked the same thing.

Deduction then told him how the Red Death was being spread!

"The water supply!" he guessed with exactness.

He showed Long Tom, Johnny, Ham, and Renny how to administer the opiates that lessened suffering.

"Monk, your knowledge of chemistry is going to be in need," he declared. "Come on."

Securing test tubes for obtaining samples of the water, Doc and Monk hurried toward the gleaming yellow pyramid.

Although the epidemic of Red Death had been under way less than an hour, the cult of red-fingered warriors had been making full use of the panic it engendered. They were falling over themselves to spread word that the disease was a punishment inflicted upon the Mayans for permitting Doc and his friends to remain in the Valley of the Vanished.

Ominous mutterings were arising. Blue-girdled men everywhere harangued madly, seeking to fan the flames of hatred.

"And just when things were sailing smooth for us!" Monk muttered.

Doc and Monk reached the golden pyramid and started up. Instantly a loud roar of anger lifted from a crowd of Mayans who had followed them. The crowd was composed of about half red-fingered fighting men.

They made threatening gestures, indicating Doc and Monk should not ascend the pyramid. It was an altar, inviolate to their gods, they screamed. Only Mayans could ascend without bringing bad luck.

It was the red-fingered men who howled the loudest.

"We're going to have a fight on our hands if we go up," Monk whispered.

It was Doc who solved the delicate situation. He did it simply. He beckoned to attractive Princess Monja, gave her the test tubes, and told her to dip water from whatever sort of a tank or pool was on top of the pyramid.

The confidence the young woman showed Doc did its bit to allay the anger of the Mayans.

Back at the stone house assigned himself and his friends, Doc set to work.

He had brought a compact quantity of apparatus. And Monk had his tiny, wonderfully efficient chemical laboratory. Doc combined the two, went to work analyzing the water.

He had trouble with the Mayans before he had hardly started. Two of the homeliest of the ugly, red-fingered gentry came dancing and screaming into the place. They had rubbed some evil-smelling lotion on themselves, and the odor angered Doc, who depended a great deal on his sense of smell in his analyzing.

Doc kicked both warriors bodily outdoors. For a moment it looked like the house was going into a state of siege. Hundreds of Mayans shrieked and waved arms and weapons outside. It was astounding the number of spears and terrible clubs they had unearthed.

But memory of what had happened to the gang of warriors who had attacked Doc the day before made them hesitate.

"Monk," Doc questioned, "did you bring that gas you made up in my laboratory in New York? The stuff that paralyzes without harming, I mean."

"I sure did," Monk assured him. "I'll go get it."

Doc heaved the heavy stone door shut and continued his analyzing.

Rocks began to bounce against the stone walls and the flat stone roof. A couple whizzed in the square window.

The yelling has risen to a bedlam.

Suddenly the note of the howling changed from rage to fear. It diminished greatly in volume. Doc looked out the window

Monk had broken a bottle of his gas where the wind carried it over the besieging Mayans. Fully half of the malefactors were stiff and helpless on the earth. They would be thus for possibly two hours, then the effects would wear off.

This eased the tension for a time, enabling Doc to continue his work undisturbed.

Test after test he ran on the water. He had very early isolated a tiny quantity of red, viscous fluid which he had determined was some sort of germ culture. The question was to find out what kind of germs.

There was not much time. His father had succumbed less than three days after being stricken. Probably that was about the time required for the ghastly disease to prove fatal.

An hour dragged past. Another. Doc worked tirelessly, with every ounce of his enormous concentration.

The humor of the Mayans rapidly became worse. Johnny, Ham, and Renny were driven to the stone house where Doc worked. They were joined by elderly King Chaac and entrancing Princess Monja. Of all the Mayans, the faith of these two in Doc remained utterly unshaken.

However, there were other Mayans who remained aloft from the turmoil — people who would probably side with Doc when the show-down came.

Doc worked without hardly lifting his head all that afternoon. He labored the night straight through, his experiments lighted by electric bulbs Long Tom fixed up.

Another dawn had come before Doc straightened from the stone bench where he had placed his apparatus.

"Long Tom!" he called.

Long Tom sprang to Doc's side and listened to Doc explain what was wanted.

It was an intricate apparatus Long Tom was to rig, a mechanism to create one of the newest and most marvelous healing rays known to medical science. Long Tom, electrical wizard that he was, knew pretty much how it should be made. Doc supplied such details as Long Tom was not familiar with.

Then Doc quitted the stone building.

His friends flocked to the doors and windows, armed with machine guns, Monk with his gas bombs. They were certain Doc would be attacked by the Mayans, who had kept vigil outside all night.

But they witnessed something little short of a miracle — Doc walked through the crowd untouched! Not a warrior dared lay a hand upon him, such a hypnotic quality did his golden eyes contain. No doubt his reputation of a superman in a fight helped.

Fifty or so Mayans trailed Doc. Afraid to attack him, they nevertheless followed him. But not for far.

Doc reached the jungle-carpeted lower end of the little valley. With a bound he lifted high from the earth and seized a limb. A monkey-like flip put him atop it. He ran along it, balancing perfectly, and sprang to another bough.

Then he was gone, silent as a bronze owl flittiing along the jungle lanes.

The Mayans milled a while, then returned to their city. They were met by a group of red-fingered fellows who upbraided them fiendishly for permitting Doc to walk through their hands. The white man, they screamed, must be slaughtered.

Somebody had freed squat, tattooed, ugly Morning Breeze from his dungeon. He was rapidly whipping the Mayans into a frenzy. He herded them toward the stone house where Doc's friends were barricaded. Exerting all his powers of persuasion, Morning Breeze got them to attack.

Monk promptly expended all his gas on the assailants. They fled, such of them as could, repulsed. But they reunited at a short distance, a great mob, and listened to the red-fingered men talk.

Now and then a Mayan would stumble off to his stone home, seized with the horrible Red Death. Perhaps a fourth of the tribe were already prostrate from the malady.

Half the morning had gone when Doc returned. He came via the roofs of the closely spaced houses, crossing the narrow streets with gigantic leaps only he could manage. He was inside the stone house with his besieged friends before the Mayans even awakened to his nearness.

The natives sent up a rumble of anger, but did not advance.

Doc had brought, tied with roots in a great bundle, many types of jungle herbs.

With these he set to work. He boiled some, cooked others, treated some with acids. Slowly he refined the product.