For the next three days the boat was worked steadily up the river; paddled swiftly through long stretches of tranquil water; hauled up falls; dragged through rapids and ever penetrated deeper and deeper into the heart of the vast wilderness.

From time to time they had met Indians, sometimes individuals paddling silently close to shore in tiny canoes of bark which Mr. Thorne said were known as “wood skins”; sometimes families in big dugouts accompanied by flea-bitten, woefully thin dogs, naked brown children and all their household belongings, and once they had paddled up a creek and had visited a large Indian village where the boys had found a thousand things to interest them.

But while every Indian was questioned, few could give any information in regard to the plane, although many had seen or heard it as it had flown southward more than a week before.

Each day and every night too, the boys had listened at their radio sets, but no more messages from the plane had been heard and all had begun to think that the aircraft had departed and that the long journey would prove fruitless. The boys, however, had had the time of their lives. They had taken numerous trips into the bush with Joseph and the other Indians. They had shot deer, wild turkeys, peccaries and a tapir, while a splendid jaguar skin and two beautiful ocelot hides were safely stowed among their belongings as trophies of their prowess as hunters, and Rawlins treasured a huge snake skin from a twenty foot anaconda that he had secured.

Much of Mr. Pauling’s time had been spent trying to decipher the messages the boys had received from the plane and the “reds’” confederate, for it was his boast that there never had been a secret code which he could not interpret.

“I guess I’ve had my trouble for nothing,” he announced one afternoon. “I’ve got it, but as I expected, it’s in some foreign tongue--Russian most likely. Yet it doesn’t look exactly like Russian either. It’s not German, but whatever it is, it’s no value to us now. Of course, we can get it translated eventually, but I’d give a lot to know what it says.”

“May I see it?” asked the explorer. “Possibly I may be able to identify it, even if I can’t read it.”

“Certainly,” replied Mr. Pauling, handing him the sheet he had covered with writing.

Mr. Thorne glanced at the paper. “Why, it’s Dutch!” he exclaimed. “Here, Colcord, can you read this?”

The Boviander fished a pair of battered spectacles from his pocket, adjusted them low on his nose and looking, as Tom said, as grave as if he were about to preach a sermon, he peered at the writing.

“Yes, sir, Chief,” he declared after a minute’s study. “I ’spec’ I can. I don’ comprehen’ Dutch too much, Chief; but I can tell yo’ what it mean.”

“All right, what is it?” replied Mr. Pauling.

“This firs’ one say as how they need help,” declared the Boviander, as he ran his blunt brown forefinger along the lines. “It say how they bus’ up the apperatix an’ can’t fly an’ don’ have food.”

“By Jove!” cried Mr. Pauling. “That’s good! Machine disabled, eh? Good for you, Colcord, we’ll get them yet. Go on, what’s next?”

The Boviander grinned and peered about over his spectacles vastly pleased to find himself the center of interest and able to exhibit his superior knowledge. Then, again studying the writing, he continued:

“I can’t ’lucidate all the words, Chief. But here ’bout it say something ’bout the ship bein’ los’ and some fellow makin’ afraid for to talk.”

“Jove! then they know the Devon’s taken,” ejaculated Mr. Henderson, “and whoever was talking has got cold feet and has quit. That’s the reason we heard nothing more. Is there anything else, Colcord?”

“Plenty else,” replied the captain, “but this specie of Dutch I don’ rightly know, Chief.”

“Well, by the great horn spoon, we’ve found out all we want to know!” exclaimed Rawlins. “They’re here; they’re helpless--at least as far as getting away is concerned--and they’re short of grub. By glory! my hunch is working out O. K., I’ll say.”

Only two days’ travel now lay between them and the Maipurisi district where the plane was supposed to be and as they gathered about the camp fire that night, plans were discussed and formed as to their actions and procedure when they neared the hiding place of the two fugitive criminals.

“I think the best plan is to run up Unuko Creek,” said Mr. Thorne. “It’s scarcely ten miles across from there to Maipurisi and we can send a couple of the Bucks over to scout and report. Then, when we locate the plane, we can go overland, surround them and call upon them to surrender while we are hidden in the bush. As they can’t get off in the plane and have no boat or canoe, they’ll be helpless.”

“Yes, that sounds like a good scheme,” agreed Mr. Pauling, “but can you be sure your Indians will manage to keep out of sight? Moreover, if by chance they were seen or captured, are you sure they would not give away our presence?”

The explorer smiled. “If you’d ever seen one of these Indians stalk game you would not ask the first question,” he replied. “Do you notice that they always use small bore, muzzle-loading guns and double ‘B’ shot and yet they kill tapir and jaguar? They could only do that by getting so close to their quarry that the light charge of shot acts like a solid ball. In other words, they creep within a dozen feet of the most wary creatures in the South American jungle and an Indian who can do that could sneak into those fellows’ camp and be within arm’s reach without being seen or heard. As for being captured, why there’s no more chance than of capturing a ghost! And if by a miracle they were seen why should those rascals ever suspect the Bucks knew anything about them or us, or had any connection with officers whom they probably imagine are hundreds of miles distant? No, don’t worry on that score.”

At this moment a low, plaintive, long-drawn whistle was borne faintly from the forest across the stream and instantly the Indians leaped up and stood motionless, listening intently and peering apprehensively across the river.

Once more, from the black depths of the jungle, came the mysterious sound and hastily gathering up their half-finished meal, the Indians came crowding close to the group of white men.

“Eh, eh, Joseph! Why makeum for ’fraid like so?” queried Mr. Thorne. “What you sabby?”

Joseph turned fear-wide eyes and terrified features towards the explorer. “Kenaima!” he exclaimed in a whisper.

Mr. Thorne whistled. “So that’s it!” he ejaculated. Then, turning to the Indians, “No makeum ’fraid, Joseph! Kenaima no makeum walk this side. No huntum you fellow Buckman same way!”

“Please tell us, what does he mean?” begged Tom, utterly at a loss to understand what had frightened the Indians or what the explorer was talking about. “What is a Kenaima?”

“The blood avenger,” replied Mr. Thorne in a low voice. “If an Indian is killed, tribal law demands that his slayer must be destroyed, and not only the assassin must pay the penalty but all his relatives as well. The man chosen to wreak vengeance is the ‘Kenaima’ or, as the Indians believe, a man in whom the spirit of vengeance takes up its abode until its mission is accomplished. Until the Kenaima kills his victim he cannot see or speak to any living being, but must live alone, ever trailing the one he seeks until he has wreaked vengeance. He may chose either one of two forms--the ‘tiger Kenaima’ or the snake or ‘camudi Kenaima.’ If the former, he must strike down his man with a short club, if the latter he must strangle him, but in either case he must not kill his victim outright at once. Instead he must disable him and then return three days later when the wounded man is put out of his misery by the Kenaima driving a wooden spear through his body. Then the avenger must lick the blood from the spear or--so they believe--the spirit of vengeance will not leave and the Kenaima will go mad, ranging the forests and killing all he meets.”

“Uugh! it makes me shiver,” cried Tom, edging closer to his father and the fire.

“And I thought these Indians were peaceable!” exclaimed Frank as he glanced nervously about.

“So they are--usually,” declared Mr. Thorne. “But they have their own laws and customs and the Kenaima is one of them. Nothing can stamp it out.”

“By glory, I’d hate to kill one of them!” exclaimed Rawlins. “But what happens if the fellow gets away--reaches civilization for instance?”

“He never gets away,” the explorer informed him gravely. “The Kenaima is tireless, relentless. If one is killed, another takes his place and there are two deaths to avenge. Why, I’ve known a Kenaima to trail his victim into Georgetown and strike him down on the street!”

“By Jove!” ejaculated Mr. Pauling. “And these Indians think there’s one about, eh?”

“They think that whistle was one,” replied Mr. Thorne. “I can’t say, but I know the Bucks claim the Kenaima warns friends to keep away by uttering a whistling sound. He must not be seen and the Indians are deathly afraid when they hear it. No power on earth could induce one of these men to cross that river to-night or to enter the jungle over there to-morrow.”

“Great Scott, I don’t blame ’em!” declared the diver. “Say, I wonder who the poor devil is that he’s after!”

“Gosh I won’t be able to sleep to-night,” said Tom. “It makes my blood run cold, just to think of it.”

“Nonsense!” exclaimed his father. “Probably that whistle was merely a night bird of some sort. These Indians are superstitious and imagine all sorts of things. Besides, we have nothing to fear. None of us has injured an Indian.”

But despite Mr. Pauling’s assurances and the fact that after a time the Indians gradually drifted back to their own fire and crawled into their hammocks, the boys tossed and remained wakeful for hours, starting up at each unusual sound and listening with straining ears for the uncanny, mysterious whistle. But it was not repeated and at last, worn out and sleepy, the boys’ drowsiness overcame their nervous fears and the gruesome blood avenger was forgotten in a dreamless slumber.

With the bright sunshine of the following day it seemed very silly to have been afraid of the supposed Kenaima and the boys discussed it without the least shivery sensations running up and down their spines as had been the case the night before. But they noticed that as the boat left camp, the Indian paddlers kept close to shore and glanced furtively across the river and that even Colcord seemed to feel relieved when they reached a bend and the locality of the strange whistling sound was left astern.

But even then the Indians acted strangely. Heretofore, they had laughed and joked or had sung rollicking chanteys in unison to the strokes of their paddles, but to-day they were quiet, talking together in low tones, constantly edging the boat towards the center of the river, despite Colcord’s efforts and commands, and plying their paddles more vigorously than ever before.

“I believe there’s something afoot,” declared Mr. Thorne. “I’ve lived a long time among these people and I’m convinced they have a sixth sense--mental telepathy or something--by which they know intuitively when there is danger near and I’m beginning to think that there may be a Kenaima about.”

“Why don’t you ask them?” inquired Mr. Henderson.

“Torture wouldn’t force them to tell,” responded the explorer. “Even to mention the avenger by name is considered dangerous--I’m surprised that Joseph dared utter the word last night.”

“But if he’s only after one person, why should they he afraid?” asked Frank. “They know he’s not after them.”

“Very true,” replied Mr. Thorne. “But they fear that he may not have driven the spirit of vengeance from his body--if he’s killed his man--and that being the case he is liable to kill and attack any one.”

“Hmm, uncomfortable sort of chap to have at large in the bush,” commented Mr. Pauling. “Does that ever occur?”

“Yes, frequently,” said Mr. Thorne. “It may seem preposterous to us, but the Indians believe so thoroughly in their superstitions that if a Kenaima does not succeed in carrying out his entire purpose he goes crazy and does run amuck.”

“Ah, I understand, sort of auto suggestion,” remarked Mr. Pauling.

It was now time to think of stopping for the noonday rest and lunch and at Mr. Thome’s orders, Colcord headed the boat towards shore.

Instantly, the Indians stopped paddling, jabbered excitedly together and then one of their number spoke vehemently to the Boviander in the Akawoia tongue.

“He say they not goin’ make camp ashore, Chief,” announced Colcord. “They boun’ for to make stop at a islan’.”

Mr. Thorne raised his eyebrows, “Oh, very well,” he replied. “It’s just the same as far as I’m concerned.”

“Not taking any chances, I see,” laughed Mr. Henderson as the mollified Indians again took up their paddles and headed for a small barren island in midstream.

While Sam was cooking lunch, the two boys and Rawlins strolled about the island, hunting for turtle eggs in the sand and amusing themselves by chasing the big lizards that ran scuttling across the pebbles.

As they reached the upper end of the island, the river beyond a sharp turn came in view and the boys called the diver’s attention to hundreds of great black birds, wheeling and circling above the trees half a mile distant.

Rawlins looked at them a moment. “They’re buzzards,” he announced. “Vultures--wonder what they’ve found up there.”

“Gee, but there’s a bunch of them!” exclaimed Tom.

Then, at Sam’s shout, they hurried back to the boat and busied themselves with their meal.

As the boat once more moved upstream and passed the island, the great flock of buzzards still soared in the clear blue sky above the forest.

“What do you suppose they’ve found?” Frank inquired of the explorer. “They were there when we walked about the island. Isn’t it funny they don’t go down and eat if they’ve found a dead animal?”

“Possibly it’s a wounded creature,” replied Mr. Thorne. “They often follow a sick or injured animal until it dies. Or again there may be a king vulture there. The black rascals won’t dare touch carrion until the king’s gorged himself.”

“King vulture!” exclaimed Tom. “What’s he?”

“It’s a large species of vulture--light colored--sort of creamy white with red and blue head, and nearly as big as a condor. They always go singly and if one of them alights near a carcass, the black vultures keep off until he’s finished. That’s why they’re called king vultures.”

“I’d like to see one,” declared Frank. “Let’s go over and see if he’s there and what they’ve found.”

“Very well,” laughed Mr. Thorne, glad to humor the boys’ curiosity. “Whatever it is, is near the river. Colcord, run over to that point and we’ll have a look at what the buzzards are after.”

As the boat approached the spot, the boys saw that trees and rocks were black with the loathsome birds which rose on flapping wings as the craft touched the shore and the boys and the others sprang on to the rocks.

Whatever had attracted the scavengers was evidently just within the verge of forest and climbing the bank, Rawlins, who was in advance, saw a huge white and black bird flap up from a clump of grass a few yards away.

“There goes the old king!” he exclaimed.

Anxious to catch a glimpse of the great bird, the boys stopped and craned their necks and the diver stepped forward towards the clump of coarse grass.

The next instant a cry of mingled horror and surprise rang through the forest and Rawlins, pale and with a strange expression on his face, came hurrying back.

“Don’t go in there!” he cried. “Come on back to the boat, boys!”

“But what--what is it?” cried Tom. “What did you see? You look as if you’d seen a ghost!”

“Worse!” exclaimed the diver. “It’s a man! A man staked out--”

“A man!” yelled Frank and then, seized with sudden terror, the two boys turned and fled headlong towards the boat.

“You mean there’s a human body in there?” demanded Mr. Pauling who, attracted by Rawlins’ excited tones, had hurried forward. “Come on, brace up, Rawlins! A dead man can’t hurt you! We can’t leave a human being to be eaten by vultures.”

With a great effort, Rawlins recovered himself. “Guess it was the shock of seeing him,” he declared, rather shamefacedly. “But by glory, it is a rotten sight!”

“Rotten or not we’ll have to bury him,” declared Mr. Pauling. “He’s an Indian I suppose.”

“Indian nothing!” cried Rawlins. “That’s the worst of it! It’s a white man!”

“By Jove!” ejaculated Mr. Pauling. “Who could it be?”

The next instant they had reached the thicket and at the sight which greeted them, even Mr. Pauling, Mr. Henderson and the explorer drew back filled with nauseating horror.

Stretched at full length upon the ground was the body of a man, with a long staff of wood driven between his shoulders and pinning him to the earth. And then, as they took a second glance, horror gave way to amazement, for fringing the dead man’s face pressed against the forest floor was a huge red beard!

“Jumping Jupiter, it’s he!” cried Rawlins. “Old Red Whiskers himself!”

“And killed by a Kenaima!” exclaimed Mr. Thorne.

“Jove, no wonder those Indians were nervous!” ejaculated Mr. Pauling.

“I’ll say they had reason to be!” declared Rawlins. “But what in blazes started a Kenaima after this guy do you suppose?”

Mr. Thorne had stepped to the edge of the trees. “Come here, Colcord,” he called, “and bring a couple of shovels along. Better bring Sam too. No use trying to get one of the Bucks.”

But when the Boviander arrived, he took one glance at the body and then, throwing down the shovels raced back to the boat. Too much Indian blood flowed in his veins for him to approach a victim of the Kenaima and as he reached the boat a low, terrified wail arose from the throats of the Indians: “Kenaima! Kenaima! Kenaima!”

Leaping into the craft they seized their paddles.

“Come on!” shouted Mr. Thorne. “Run for your lives! They’re crazed with fear! They’re going off!”

Shouting to Colcord and the Indians, the explorer tore down the bank and across the rocks with the others at his heels. Already the boat was several yards from land, but as he heard Mr. Thorne’s commands and realized what he was doing, Colcord checked the boat, uttered sharp orders to the Indians and with Sam’s help swung the boat ashore. The four men and the boys leaped in and instantly the terrified Indians dug their paddles into the stream and drove the boat madly from the accursed spot.

“Too bad, but it can’t be helped,” muttered Mr. Thorne. “I hate to leave him, but there’s nothing to be done.”

“Well, he’s tossed many a poor devil to the sharks!” exclaimed Rawlins. “So I guess it kind of evens up things. But by glory, I’d like to know where his mate is.”