Doc guided Ham and Monk outside They turned left. Doc seized Ham and gave him a toss that lifted him to a low roof. Monk managed the jump unassisted, and Doc followed. They leaped to another roof, another.

On that one lay the silken folds of a parachute.

"That's how I got here," Doc explained. "News of that fight you had spread fast. I heard it and took off in the plane. Two thousand feet up I touched off a parachute flare. That lighted the whole town. I was lucky enough to see the gang haul you into that joint. So I simply jumped down to help you."

"Sure!" Monk grinned. "There wasn't nothin' to it, was there, Doc?"

Doc, Ham, and Monk strolled through the moonlight to the spot on the lake shore where they had pitched camp. A crowd of curious natives were there inspecting the plane, talking among themselves. Aircraft were still a novelty in this out-of-the-way spot.

Doc, a bronze giant nearly twice as tall as some of the swarthy fellows, mingled among them and asked questions in the mixture of Spanish and Indian lingo they spoke. He wanted to know about the blue plane which had attacked him at Belize

The blue plane had been seen a few times by the natives. But they did not know from whence it came or where it went.

Doc noticed some of the swarthy little men were very superstitious about the blue plane. These would give him little information. In each case the features of such men showed they were of Mayan ancestry.

Doc recalled then that blue was the sacred color of the ancient Mayans. It only added to this mysterious thing confronting him.

Renny and the others had erected a silken tent. But they had also dug inside the tent a deep hole, sort of a dugout in which to sleep. From the outside, the excavation would escape detection. They were taking no chance on a sudden machine-gun burst in the night.

Monk and Ham, completely recovered from their narrow brush with death, decided to sleep in the plane cabin, alternating on keeping guard.

Doc himself set off alone through the night. Thanks to the marvelous faculties he had developed by years of intensive drill, he had little fear of his enemies attacking him successfully.

He went to the presidential palace. To the servant who admitted him, Doc gave simply his name and a request to see the President of Hidalgo.

In a surprisingly brief interval, the flunky was back. Carlos Avispa, President of Hidalgo, would see Doc at once.

Doc was ushered into a great, sumptuously fitted room. The chamber was in twilight, and a small motion-picture projector was throwing shifting images onto a white screen. However, the film being run off was one concerning military tactics instead of a mushy love drama.

Carlos Avispa came forward with a warmly outstretched hand. He was a powerful man, a few inches shorter than Doc. His upstanding shock of white hair lent him a distinguished aspect. His face was lined with care, but intelligent and pleasant. He was near fifty.

"It is a great honor indeed to meet the son of the great Senor Clark Savage," he said with genuine heartiness.

That surprised Doc. He was not aware his father had known Carlos Avispa. But Doc's father had many friends of whom Doc was not aware.

"You knew my father?" Doc inquired.

Carlos Avispa bowed. There was genuine esteem in his voice as he replied: "Your father saved my life with his wonderful medical skill. That was twenty years ago, when I was but an unimportant revolutionist hiding out in the mountains. You, I believe, are also a great doctor and surgeon?"

Here was a break, Doc reflected. He nodded that he was a doctor and surgeon. For that was the thing he knew more about than all others.

In the course of a few minutes Doc had told his story and mentioned that Don Rubio Gorro, the Secretary of State, had refused to honor his grant to the territory in interior Hidalgo.

"I shall remedy that at once, Senor Savage." declared President Carlos Avispa. "Anything I have, any power I control, is yours."

After he had thanked the elderly, likable man properly, Doc inquired whether President Avispa had any idea what made the tract of land so valuable that many men were anxious to do murder to prevent him reaching it.

"I cannot imagine," was the reply. "I do not know what your father found there. He was bound for the interior of Hidalgo when he came upon me ill in camp twenty years ago. He saved my life. And I never saw him again. As for the region, it is very near impregnable, and the natives are so troublesome I have given up trying to send soldiers to explore."

President Carlos Avispa reflected deeply, then went on.

"It worries me, this action of my Secretary of State, Don Rubio Gorro," he said. "Some sneak has destroyed the records of this heritage your father left you. They should be in our archives. But I cannot understand why Don Rubio should act as he did. Your papers were enough, even though ours had vanished. He shall be punished for his impertinence."

Doc was silent. The moving-picture machine was still running off the reel of military maneuvers — the type of picture shown at war colleges.

With a smile, President Avispa indicated the cinema machine. "I must keep myself advised of the latest fighting methods. It is indeed regrettable. But it seems we can never have peace here in the south. There is always a revolution brewing.

"Just recently I have heard strong rumors that an attempt is to be made to assassinate me and seize power. Many of my people of Mayan ancestry are involved. But I do not know the ringleaders. I understand they await only money to buy arms before making the attempt."

There came into the elderly chief executive's eyes a fiery, warlike glint.

"If I could but find from what source their money is expected to come, I would soon put a quietus on them. And, best of all, it would be done without bloodshed!"

Doc conversed for a considerable time, mostly about his great father. Politely declining an invitation to spend the night at the presidential palace, he departed at a late hour.

Striding through Blanco Grande's sleepy streets, Doc was thoughtful. Could it be that the money for the revolution against President Carlos Avispa was tied up directly with his heritage? The fact that Mayans were involved in both pointed that way. Maybe his enemies were trying to rob him of his legacy; and use it to finance a revolution to overthrow President Avispa!

The enemies had tried hard enough from the first to prevent him even finding out about the legacy. Strange — the whole thing!

Then Doc stopped suddenly.

Before him on the dimly moonlit cobbles lay a knife. It had an obsidian stone blade, a hilt of wound leather — exactly such a knife as the Mayan in New York had carried.

Some fifteen minutes later, there was a curious meeting in a top-floor room of Blanco Grande's one hotel modern enough to be fitted with running water and a radio in every room. The hotel happened to be the pride of all Hidalgo. Three stories high!

But the gentry meeting in the top-floor room were easily the scourge of Hidalgo. They were the ringleaders of the latest crop of revolutionists. These men were motivated by no high ideals of freedom. If so, they wouldn't have been here, because no kinder or more upright official ever administered a nation than elderly President Carlos Avispa.

Greed was behind every act of these men. They wanted to overthrow President Avispa's honest, low-cost government, so they could loot the public treasury, tax the citizens to bankruptcy for a year or two, then skip to Paris and the fleshpots of Europe for a life of luxury on the proceeds.

Eleven outlaws from the hills were congregated on one side of the room. Shaggy, vicious fellows, every one of them was a murderer many times over.