Eastward. Bell had overshot the mark the night before. Before he had located himself he was quite fifty miles beyond the spot Paula had suggested as a hiding place. Now he retraced his way. A peak jutting up from far beyond the horizon was a guiding mark. He set the plane's nose for it, and relaxed.

The motor thundered on valorously. Far below was a vast expanse of thick jungle, intercepted but nowhere broken by occasional small streams and now and then the tiny, angular things which might be houses. But houses were very infrequent. In the first ten miles--with a view of twenty miles in every direction--Bell picked out no more than four small groups of buildings which might be the unspeakably isolated _fazendas_ of the folk of this region.

"Ribiera was coming this way," he muttered.

He fumbled the headphone of the radio set into place. The set seemed to be already arbitrarily tuned. He turned it on. There was a monotonous series of flashes, with the singing note of a buzzer in them. A radio direction signal.

"Ribiera's on the way."

Bell stared far ahead, without reason. And it seemed to him that just then, against that far distant guiding peak, he saw a black speck floating in mid-air.

He pulled back the joy stick. Detached, feathery clouds spread across the sky, and he was climbing for them. Paula looked behind at him, and he pointed. He saw her seem to stiffen upon sight of the other aircraft.

In minutes Bell's plane was tearing madly through sunlit fleecy monsters which looked soft and warm and alluring, and were cold and damp and blinding in their depths. Bell kept on his course. The two planes were approaching each other at a rate of nearly two hundred miles an hour.

And then, while the harsh, discordant notes of the radio signal sounded monotonously in his ears, Bell stared down and, through a rift between two clouds, saw the other plane for an instant, a thousand feet below.

The sun shone upon it fiercely. Its propeller was a shimmering, cobwebby disk before it. It seemed to hang motionless--so short was Bell's view of it--between earth and sky: a fat glistening body as of a monstrous insect. Bell could even see figures in its c.o.c.kpits.

Then it was gone, but Bell felt a curious hatred of the thing. Ribiera was almost certainly in it, headed for the place to which he had spoken the night before. And Bell was no longer able to think of Ribiera with any calmness. He felt a personal, gusty hatred for the man and all he stood for.

His face was grim and savage as his own plane sped through the clouds.

But just as the two aircraft had approached each other with the combined speed of both, so they separated. It seemed only a moment later that Bell dipped down below the clouds and the other plane was visible only as a swiftly receding mote in the sunlight.

"I wonder," said Bell coldly to himself, with the thunder of the motor coming through the singing of the air route signal, "I wonder if he'll see the ship I cracked up last night?"

Paula was pointing. The shoulder of a hill upthrust beneath the jungle. The tall trees were cleared away at its crest. Small, whitewashed buildings appeared below.

"Good landing field," said Bell, his eyes narrowing suddenly. "On the direct route. Fifty miles back there's another landing field. I wonder...."

He was already suspicious before he flattened out above the house, while dogs fled madly. He noticed, too, that horses in a corral near the buildings showed no signs of fright. And horses are always afraid of landing aircraft, unless they have had much opportunity to grow accustomed to them.

The little plane rolled and b.u.mped, and gradually came to a stop. Bell inconspicuously shifted a revolver to the outer pocket of his flying suit. Figures came toward them, with a certain hesitating reluctance that changed Bell's suspicions even while it confirmed them.

"Paula," he said grimly, "this is another landing field for Ribiera's emergency use. It sticks out all over the place. Relatives or no relatives, you want to make sure of them. You understand?"

Her eyes widened in a sudden startled fear. She caught her breath sharply. Then she said quietly, though her voice trembled:

"I understand. Of course."

She slipped out of the plane and advanced to meet the approaching figures. There were surprised, astounded exclamations: A bearded man embraced her and shouted. Women appeared and, after staring, embraced.

Paula turned to wave her hand rea.s.suringly to Bell, and vanished inside the house.

Bell looked over his instruments, examined the gas in the tank, and began to work over his maps in the blaring sunlight. He cut out the switch and the motor stopped with minor hissings of compression. The maps held his attention, though he listened keenly as he worked for any signs of trouble that Paula might encounter.

He was beginning to have a definite idea in his mind. Ribiera had talked to a headquarters somewhere, by beam radio from Rio. Beam wireless, of course, is nothing more or less than a concentration of a radio signal in a nearly straight line, instead of allowing it to spread about equally on all sides of the transmitting station. It makes both for secrecy and economy, since nearly all the power used at the sending apparatus is confined to an arc of about three degrees of a circle. Directed to a given receiving station, receiving outfits to one side or the other of that path are unable to listen in, and the signal is markedly stronger in the chosen path. Exactly the same process, of course, is used for radio directional signals, one of which still buzzed monotonously in Bell's ears until he impatiently turned it off. A plane in the path hears the signal. If it does not hear the signal, it is demonstrably off the straight route.

Bell, then, was in a direct line from Rio to the source of a radio direction signal. Fifty miles back, where the big amphibian had crashed, he was in the same air line. To extend that line on into the interior would give the destination of Ribiera, and the location of the headquarters where direct communication with The Master was maintained.

He worked busily. His maps were in separate sheets, and it took time to check the line from Rio. When he had finished, he computed grimly.

"At a hundred miles in hour...." He was figuring the maximum distance which could plausibly be accepted as a day's journeying by air. He surveyed the maps again. "The plateau of Cuyaba, at a guess. Hm....

Fleets of aircraft could practise there and never be seen. An army could be maneuvered without being reported. Certainly the headquarters for the whole continent could be there. Striking distance of Rio, Montevideo, Buenos Aires, La Paz, and Asuncion. Five republics."

Certainly, from his figures, it seemed plausible that somewhere up on the Plateau of Cuyaba--where no rails run, no boats ply, and no telegraph line penetrates; which juts out ultimately into that unknown region where the Rio Zingu and the Tapajoz have their origins--certainly it seemed plausible that there must lie the headquarters of the whole ghastly conspiracy. There, it might be, the deadly plants from which The Master's poison was brewed were grown.

There the deadly stuff was measured out and mixed with its temporary antidote....

Paula came back, a young man with her. Her eyes were wide and staring, as if she had looked upon something vastly worse than death.

"He--Ribiera," she gasped. "My uncle, he owned this place. They--have him here--alive--and mad! And all the rest...."

Bell fumbled in the pocket of his flying suit. The young man with Paula was looking carefully at the plane. And there was a revolver in a holster at his side. An air of grim and desperate doggedness was upon him.

"This is--my cousin," gasped Paula. "He--and his wife--and--and--"

The young man took out his weapon. He fired. There was a clanging of metal, the screech of tortured steel. Bell's own revolver went off the fraction of a second too late.

"You may kill me, Senhor," said the young man through stiff lips. His revolver had dropped from limp fingers. He pressed the fingers of his left hand upon the place where blood welled out, just above his right elbow. "You may kill me. But if you and my cousin Paula escaped.... I have a wife, Senhor, and my mother, and my children. Kill me if you please. It is your right. But I have seen my father go mad." Sweat, the sweat of agony and of shame, came out upon his face. "I fought him, Senhor, to save the lives of all the rest. And I have spoiled your engine, and I have already sent word that you and Paula are here.

Not for my own life, but...."

He waited, haggard and ashamed and desperate and hopeless. But Bell was staring at the motor of the airplane.

"Crankcase punctured," he said dully. "Aluminum. The bullet went right through. We can't fly five miles. And Ribiera knows we're here--or will."

CHAPTER IX

There was the sound of weeping in the house, the gusty and hopeless weeping of women. Bell had been walking around and around the plane, staring at it with his hands clenched. Paula watched him.

"I am thinking," she said in an attempt at courage, "that you said I must not despair without your permission. But--"

"Hush!" said Bell impatiently. He stared at the engine. "I'd give a lot for a car. Bolts.... How many hours have we?"

"Four," said Paula drearily. "Perhaps five. You have smashed the radio in the house?"